CSS Counter Styles Level 3

Abstract

This module introduces the ‘@counter-style’ rule, which allows authors to define their own custom counter styles for use with CSS list-marker and generated-content counters [CSS3LIST]. It also predefines a set of common counter styles, including the ones present in CSS2 and CSS2.1. CSS is a language for describing the rendering of structured documents (such as HTML and XML) on screen, on paper, in speech, etc.

Status of this document

This section describes the status of this document at the time of its publication. Other documents may supersede this document. A list of current W3C publications and the latest revision of this technical report can be found in the W3C technical reports index at http://www.w3.org/TR/.

Publication as a Last Call Working Draft does not imply endorsement by the W3C Membership. This is a draft document and may be updated, replaced or obsoleted by other documents at any time. It is inappropriate to cite this document as other than work in progress.

The (archived) public mailing list [email protected] (see instructions) is preferred for discussion of this specification. When sending e-mail, please put the text “css-counter-styles” in the subject, preferably like this: “[css-counter-styles] …summary of comment…”

This document was produced by the CSS Working Group (part of the Style Activity).

This document was produced by a group operating under the 5 February 2004 W3C Patent Policy. W3C maintains a public list of any patent disclosures made in connection with the deliverables of the group; that page also includes instructions for disclosing a patent. An individual who has actual knowledge of a patent which the individual believes contains Essential Claim(s) must disclose the information in accordance with section 6 of the W3C Patent Policy.

The deadline for comments is 18 August 2013.

Table of contents

1 Introduction§

CSS 1 defined a handful of useful counter styles based on the styles that HTML traditionally allowed on ordered and unordered lists. While this was expanded slightly by CSS2.1, it doesn't address the needs of worldwide typography.

This module introduces the @counter-style rule which allows CSS to address this in an open-ended manner, by allowing the author to define their own counter styles. These styles can then be used in the list-style-type property or in the counter() and counters() functions. It also defines some additional predefined counter styles, particularly ones which are common but complicated to represent with @counter-style.

2 Counter Styles§

A counter style defines how to convert a counter value into a string. Counter styles are composed of:

• a name, to identify the style
• an algorithm, which transforms integer counter values into a basic string representation
• a negative sign, which is prepended or appended to the representation of a negative counter value.
• a prefix, to prepend to the representation
• a suffix to append to the representation
• a range, which limits the values that a counter style handles
• a spoken form, which describes how to read out the counter style in a speech synthesizer
• and a fallback style, to render the representation with when the counter value is outside the counter style's range or the counter style otherwise can't render the counter value

When asked to generate a counter representation using a particular counter style for a particular counter value, follow these steps:

1. If the counter value is outside the range of the counter style, exit this algorithm and instead generate a counter representation using the counter style's fallback style and the same counter value.
2. Using the counter value and the counter algorithm for the counter style, generate an initial representation for the counter value. If the counter value is negative and the counter style is negative-capable, instead generate an initial representation using the absolute value of the counter value.
3. If the representation uses less symbols than specified in the counter style's pad descriptor, prepend symbols to the representation as specified in the pad descriptor.
4. If the counter value is negative and the counter style is negative-capable, wrap the representation in the counter style's negative sign as specified in the negative descriptor.
5. Return the representation.

Note: the prefix and suffix don't play a part in this algorithm. This is intentional; the prefix and suffix aren't part of the string returned by the counter() or counters() functions. Instead, the prefix and suffix are added by the algorithm that constructs the value of the content property for the ::marker pseudo-element. This also implies that the prefix and suffix always come from the specified counter-style, even if the actual representation is constructed by a fallback style.

3 Defining Custom Counter Styles: the @counter-style rule§

The @counter-style rule allows authors to define a custom counter style. The components of a counter style are specified by descriptors in the @counter-style rule. The algorithm is specified implicitly by a combination of the system, symbols, and additive-symbols properties.

The general form of an @counter-style rule is:

@counter-style <counter-style-name> { <declaration-list> }

The <counter-style-name> must be be a valid identifier and must not be decimal or none, or else the rule is invalid. (Note, however, that some names, like inside or initial, might conflict with the existing values of properties like list-style, and thus won't be usable there.)

Counter style names are case-sensitive. However, the names defined in this specification are ASCII lower-cased on parse wherever they are used as counter styles, e.g. in the list-style set of properties, in the @counter-style rule, and in the counter() functions.

Each @counter-style rule specifies a value for every counter-style descriptor, either implicitly or explicitly. Those not given explicit value in the rule take the initial value listed with each descriptor in this specification. These descriptors apply solely within the context of the @counter-style rule in which they are defined, and do not apply to document language elements. There is no notion of which elements the descriptors apply to or whether the values are inherited by child elements. When a given descriptor occurs multiple times in a given @counter-style rule, only the last specified value is used; all prior values for that descriptor must be ignored.

Defining a @counter-style makes it available to the entire document in which it is included. If multiple @counter-style rules are defined with the same name, only one wins, according to standard cascade rules. @counter-style rules cascade "atomically": if one replaces another of the same name, it replaces it entirely, rather than just replacing the specific descriptors it specifies.

This at-rule conforms with the forward-compatible parsing requirement of CSS; conformant parsers that don't understand these rules will ignore them without error. Any descriptors that are not recognized or implemented by a given user agent must be ignored in their entirety; they do not make the @counter-style rule invalid.

3.1 Counter algorithms: the system descriptor§

The system descriptor specifies which algorithm will be used to construct the counter's representation based on the counter value. For example, cyclic counter styles just cycle through their symbols repeatedly, while numeric counter styles interpret their symbols as digits and build their representation accordingly. The systems are defined as follows:

3.1.1 Cycling Symbols: the cyclic system§

The cyclic counter system cycles repeatedly through its provided symbols, looping back to the beginning when it reaches the end of the list. It can be used for simple bullets (just provide a single counter symbol), or for cycling through multiple symbols. The first counter symbol is used as the representation of the value 1, the second counter symbol (if it exists) is used as the representation of the value 2, etc.

If the system is cyclic, the symbols descriptor must contain at least one counter symbol, or else the @counter-style rule is invalid. This system is defined over all counter values.

@counter-style triangle {
  system: cyclic;
  symbols: ‣;
  suffix: "";
}

‣  One
‣  Two
‣  Three

If there are N counter symbols and a representation is being constructed for the integer value, the representation is the counter symbol at index ( (value-1) mod N) of the list of counter symbols (0-indexed).

3.1.2 Exhaustible Symbols: the fixed system§

The fixed counter system runs through its list of counter symbols once, then falls back. It is useful for representing counter styles that only have a finite number of representations. For example, Unicode defines several limited-length runs of special characters meant for lists, such as circled digits.

If the system is fixed, the symbols descriptor must contain at least one counter symbol, or else the @counter-style rule is invalid. This system is defined over counter values in a finite range, starting with the first symbol value and having a length equal to the length of the list of counter symbols.

When this system is specified, it may optionally have an integer provided after it, which sets the first symbol value. If it is omitted, the first symbol value is 1.

@counter-style box-corner {
  system: fixed;
  symbols: ◰ ◳ ◲ ◱;
  suffix: ':';
}

◰:  One
◳:  Two
◲:  Three
◱:  Four
5:  Five
6:  Six

The first counter symbol is the representation for the first symbol value, and subsequent counter values are represented by subsequent counter symbols. Once the list of counter symbols is exhausted, further values cannot be represented by this counter style, and must instead be represented by the fallback counter style.

3.1.3 Repeating Symbols: the symbolic system§

The symbolic counter system cycles repeatedly through its provided symbols, doubling, tripling, etc. the symbols on each successive pass through the list. For example, if the original symbols were "*" and "†", then on the second pass they would instead be "**" and "††", while on the third they would be "***"and "†††", etc. It can be used for footnote-style markers, and is also sometimes used for alphabetic-style lists for a slightly different presentation than what the alphabetic system presents.

If the system is symbolic, the symbols descriptor must contain at least one counter symbol, or else the @counter-style rule is invalid. This system is defined only over strictly positive counter values.

@counter-style footnote {
  system: symbolic;
  symbols: '*' ⁑ † ‡;
  suffix: "";
}

*   One
⁑   Two
†   Three
‡   Four
**  Five
⁑⁑  Six

@counter-style upper-alpha-legal {
  system: symbolic;
  symbols: A B C D E F G H I J K L M 
           N O P Q R S T U V W X Y Z;
}

To construct the representation, run the following algorithm:

Let N be the length of the list of counter symbols, value initially be the counter value, S initially be the empty string, and symbol(n) be the nth counter symbol in the list of counter symbols (0-indexed).

1. Let the chosen symbol be symbol(value mod N).
2. Let the representation length be floor( (value - 1) / N ).
3. Append the chosen symbol to S a number of times equal to the representation length.

Finally, return S.

The symbolic system will produce representations with sizes that are linear in the magnitude of the counter value. This can potentially be abused to generate excessively large representations and consume undue amounts of the user's memory or even hang their browser. User agents must support representations at least 20 characters long, but they may choose to instead use the fallback style for representations that would be longer than 20 characters.

3.1.4 Bijective Numerals: the alphabetic system§

The alphabetic counter system interprets the list of counter symbols as digits to an alphabetic numbering system, similar to the default lower-alpha counter style, which wraps from "a", "b", "c", to "aa", "ab", "ac". Alphabetic numbering systems do not contain a digit representing 0; so the first value when a new digit is added is composed solely of the first digit. Alphabetic numbering systems are commonly used for lists, and also appear in many spreadsheet programs to number columns. The first counter symbol in the list is interpreted as the digit 1, the second as the digit 2, and so on.

If the system is alphabetic, the symbols descriptor must contain at least two counter symbols, or else the @counter-style rule is invalid. This system is defined only over strictly positive counter values.

A counter style using go stones can be defined as:

@counter-style go {
  system: alphabetic;
  symbols: url(white.svg) url(black.svg);
  suffix: "";
}

It will then produce lists that look like:

One
Two
Three
Four
Five
Six
Seven

Note: This example requires support for SVG images to display correctly.

If there are N counter symbols, the representation is a base N alphabetic number using the counter symbols as digits. To construct the representation, run the following algorithm:

Let N be the length of the list of counter symbols, value initially be the counter value, S initially be the empty string, and symbol(n) be the nth counter symbol in the list of counter symbols (0-indexed).

While value is not equal to 0:

1. Set value to value - 1.
2. Prepend symbol( value mod N ) to S.
3. Set value to floor( value / N ).

Finally, return S.

3.1.5 Positional Numerals: the numeric system§

The numeric counter system interprets the list of counter symbols as digits to a "place-value" numbering system, similar to the default decimal counter style. The first counter symbol in the list is interpreted as the digit 0, the second as the digit 1, and so on.

If the system is numeric, the symbols descriptor must contain at least two counter symbols, or else the @counter-style rule is invalid. This system is defined over all counter values.

@counter-style trinary {
  system: numeric;
  symbols: '0' '1' '2';
}

1.   One
2.   Two
10.  Three
11.  Four
12.  Five
20.  Six

If there are N counter symbols, the representation is a base N number using the counter symbols as digits. To construct the representation, run the following algorithm:

Let N be the length of the list of counter symbols, value initially be the counter value, S initially be the empty string, and symbol(n) be the nth counter symbol in the list of counter symbols (0-indexed).

1. If value is 0, append symbol(0) to S and return S.
2. While value is not equal to 0:
   1. Prepend symbol( value mod N ) to S.
   2. Set value to floor( value / N ).
3. Return S.

3.1.6 Accumulating Numerals: the additive system§

The additive counter system is used to represent "sign-value" numbering systems, which, rather than using reusing digits in different positions to change their value, define additional digits with much larger values, so that the value of the number can be obtained by adding all the digits together. This is used in Roman numerals and other numbering systems around the world.

If the system is additive, the additive-symbols descriptor must contain at least one additive tuple, or else the @counter-style rule is invalid. This system is nominally defined over all counter values (see algorithm, below, for exact details).

@counter-style dice {
  system: additive;
  additive-symbols: 6 ⚅, 5 ⚄, 4 ⚃, 3 ⚂, 2 ⚁, 1 ⚀;
  suffix: "";
}

⚀    One
⚁    Two
⚂    Three
...
⚅⚄   Eleven
⚅⚅   Twelve
⚅⚅⚀  Thirteen

To construct the representation, run this algorithm:

Let value initially be the counter value, S initially be the empty string, and symbol list initially be the list of additive tuples.

1. If value is initially 0, and there is an additive tuple with a weight of 0, append that tuple's counter symbol to S and return S.
2. While value is greater than 0 and there are elements left in the symbol list:
   1. Pop the first additive tuple from the symbol list. This is the current tuple.
   2. Append the current tuple's counter symbol to S floor( value / current tuple's weight ) times (this may be 0).
   3. Decrement value by the current tuple's weight multiplied by the number of times the current tuple was appended to S in the previous step.
3. If the loop ended because value is 0, return S. Otherwise, the given counter value cannot be represented by this counter style, and must instead be represented by the fallback counter style.

The additive system will produce representations with sizes that are linear in the magnitude of the counter value. This can potentially be abused to generate excessively large representations and consume undue amounts of the user's memory or even hang their browser. User agents must support representations at least 20 characters long, but they may choose to instead use the fallback style for representations that would be longer than 20 characters.

Note: All of the predefined additive @counter-style rules in this specification produce representations for every value in their range, but it's possible to produce values for additive-symbols that will fail to find a representation with the algorithm defined above, even though theoretically a representation could be found. For example, if a @counter-style was defined with additive-symbols: 3 "a", 2 "b";, the algorithm defined above will fail to find a representation for a counter value of 4, even though theoretically a "bb" representation would work. While unfortunate, this is required to maintain the property that the algorithm runs in linear time relative to the size of the counter value.

3.1.7 Tweaking Existing Counter Styles: the override system§

The override system allows an author to use the algorithm of another counter style, but alter other aspects, such as the negative sign or the suffix. If a counter style uses the override system, any unspecified descriptors must be taken from the overridden counter style specified, rather than taking their initial values.

If a @counter-style uses the override system, it must not contain a symbols or additive-symbols descriptor, or else the @counter-style rule is invalid. If the specified counter style name isn't the name of any currently-defined counter style, it must be treated as if it was overriding the decimal counter style.

3.2 Formatting negative values: the negative descriptor§

The negative descriptor defines how to alter the representation when the counter value is negative.

The first <symbol> in the value is prepended to the representation when the counter value is negative. The second <symbol>, if specified, is appended to the representation when the counter value is negative.

Not all system values use a negative sign. In particular, a counter style is negative-capable is one where its system value is symbolic, alphabetic, numeric, additive, or override if the overridden counter style is itself negative-capable. If a counter style is not negative-capable, it ignores the negative sign when generating a counter representation.

3.3 Symbols before the marker: the prefix descriptor§

The prefix descripter specifies a <symbol> that is prepended to the marker representation. Prefixes are only added by the algorithm for constructing the default contents of the ::marker pseudo-element; the prefix is not added automatically when the counter() or counters() functions are used. Prefixes come before any negative sign.

3.4 Symbols after the marker: the suffix descriptor§

The suffix descripter specifies a <symbol> that is appended to the marker representation. Suffixes are only added by the algorithm for constructing the default contents of the ::marker pseudo-element; the suffix is not added automatically when the counter() or counters() functions are used. Suffixes are added to the representation after negative signs.

3.5 Limiting the counter scope: the range descriptor§

The range descriptor defines the ranges over which the counter style is defined. If a counter style is used to represent a counter value outside of its ranges, the counter style instead drops down to its fallback counter style.

auto

The range depends on the counter system. For cyclic, numeric, and fixed systems, the range is negative infinity to positive infinity. For alphabetic and symbolic systems, the range is 1 to positive infinity. For additive systems, the range is 0 to positive infinity. For override systems, the range is identical to the overridden system.

[ [ <integer> | infinite ]{2} ]#

This defines a comma-separated list of ranges. For each individual range, the first value is the lower bound and the second value is the upper bound. This range is inclusive - it contains both the lower and upper bound numbers. If infinite is used as the first value in a range, it represents negative infinity; if used as the second value, it represents positive infinity. The range of the counter style is the union of all the ranges defined in the list.

If the lower bound of any range is higher than the upper bound, the entire descriptor is invalid and must be ignored.

Implementations must support ranges with a lower bound of at least -2¹⁵ and an upper bound of at least 2¹⁵-1 (the range of a signed 2-byte int). They may support higher ranges. If any specified bound is outside of the implementation's supported bounds, it must be treated as the closest bound that the implementation does support.

3.6 Zero-Padding and Constant-Width Representations: the pad descriptor§

The pad descriptor allows an author to specify a "fixed-width" counter style, where representations shorter than the pad value are padded with a particular <symbol>. Representations larger than the specified pad value are constructed as normal.

<integer> && <symbol>

The <integer> specifies a minimum number of <symbol>s that all counter representations must reach. If a counter representation would be generated using less <symbol>s than the specified <integer> (before adding prefixes/suffixes/negatives), prepend copies of the specified <symbol> to the representation until the number of symbols reaches the specified pad value.

The <integer> must be non-negative. A negative value is a syntax error.

If the counter value is negative and the counter style is negative-capable, treat the minimum number of <symbol>s as being one or two smaller when determining how many copies to prepend, depending on whether the negative descriptor's value is one or two <symbol>s.

Note: The pad descriptor counts the number of <symbol>s used to construct the representation, not the number of characters, and also pads the representation with <symbol>s. For many styles, the distinction is irrelevant, as all the <symbol>s are single-chararacter, but if a style uses multi-character <symbol>s, care must be taken not to accidentally specify pad in terms of characters.

3.7 Defining fallback: the fallback descriptor§

The fallback descriptor specifies a fallback counter style to be used when the current counter style can't create a representation for a given counter value. For example, if a counter style defined with a range of 1-10 is asked to represent a counter value of 11, the counter value's representation is instead constructed with the fallback counter style (or possibly the fallback style's fallback style, if the fallback style can't represent that value, etc.).

If the value of the fallback descriptor isn't the name of any currently-defined counter style, the used value of the fallback descriptor is decimal instead. Similarly, while following fallbacks to find a counter style that can render the given counter value, if a loop in the specified fallbacks is detected, the decimal style must be used instead.

Note that it is not necessarily an error to specify fallback loops. For example, if an author desires a counter style with significantly different representations for even and odd counter values, they may find it easiest to define one style that can only represent odd values and one that can only represent even values, and specify each as the fallback for the other one. Though the fallback graph is circular, at no point do you encounter a loop while following these fallbacks - every counter value is represented by one or the other counter style.

3.8 Marker characters: the symbols and additive-symbols descriptors§

<symbol> = <string> | <image> | <ident>

The symbols and additive-symbols descriptors specify the symbols used by the marker-construction algorithm specified by the system descriptor. The symbols descriptor must be specified if the counter system is cyclic, numeric, alphabetic, symbolic, or fixed, and the additive-symbols descriptor must be specified if the counter system is additive; otherwise, the @counter-style is invalid and must be ignored.

Some counter systems specify that the symbols descriptor must have at least two entries. If the counter style's system is such, and the symbols descriptor has only a single entry, the counter style is invalid and must be ignored.

Each entry in the symbols descriptor's value defines a counter symbol, which is interpreted differently based on the counter style's system. Each entry in the additive-symbols descriptor's value defines an additive tuple, which consists of a counter symbol and a non-negative integer weight. Each weight must be a non-negative integer, and the additive tuples must be specified in order of descending weight; otherwise, the @counter-style is invalid and must be ignored.

Counter symbols may be strings, images, or identifiers, and the three types can be mixed in a single descriptor. Counter representations are constructed by concatenating counter symbols together. Identifiers are rendered as strings containing the same characters. Images are rendered as inline replaced elements. The default object size of an image counter symbol is a 1em by 1em square.

Note: If using identifiers rather than strings to define the symbols, be aware of the syntax of identifiers. In particular, ascii non-letters like "*" are not identifiers, and so must be quoted in a string. Hex escapes, used in several of the counter styles defined in this specification, "eat" the following space (to allow a digit to follow a hex escape without ambiguity), so two spaces must be put after a hex escape to separate it from the following one, or else they'll be considered adjacent, and part of the same identifier.

3.9 Speech Synthesis: the speak-as descriptor§

A counter style can be constructed with a meaning that is obvious visually, but impossible to meaningfully represent via a speech synthesizer, or possible but nonsensical when naively read out. The speak-as descriptor describes how to synthesize the spoken form of a counter formatted with the given counter style. Values have the following meanings:

auto

If the counter style's system is alphabetic, this value computes to alphabetic. If the system is cyclic, this value computes to bullet. Otherwise, this value computes to numeric.

numeric

The counter's value is spoken as a number in the document language.

alphabetic

Generate a counter representation for the value as normal, then spell it out letter-by-letter in the document language. If the UA does not know how to pronounce the symbols, it may handle it as numeric.

For example, lower-greek in English would be read out as "alpha", "beta", "gamma", etc. Conversely, upper-latin in French would be read out as (in phonetic notation) /a/, /be/, /se/, etc.

bullet

The UA speaks a UA-defined phrase or audio cue that represents a list item being read out.

<counter-style-name>

The counter's value is instead spoken out in the specific style. If the specified style does not exist, this value is treated as auto.

@counter-style circled-lower-latin {
  system: alphabetic;
  speak-as: lower-latin;
  symbols: ⓐ ⓑ ⓒ ⓓ ⓔ ⓕ ⓖ ⓗ ⓘ ⓙ ⓚ ⓛ ⓜ ⓝ ⓞ ⓟ ⓠ ⓡ ⓢ ⓣ ⓤ ⓥ ⓦ ⓧ ⓨ ⓩ;
  suffix: "";
}

4 Defining Anonymous Counter Styles: the symbols() function§

The symbols() function allows a counter style to be defined inline in a property value, for when a style is used only once in a stylesheet and defining a full @counter-style rule would be overkill. It does not provide the full feature-set of the @counter-style rule, but provides a sufficient subset to still be useful. The syntax of the symbols() rule is:

  symbols() = symbols( <symbols-type>? [ <string> | <image> ]+ );
  <symbols-type> = cyclic | numeric | alphabetic | symbolic | fixed;

The symbols() function defines an anonymous counter style with no name, a prefix and suffix of "" (the empty string), a range of auto, a fallback of decimal, and a negative of "\2D" ("-" hyphen-minus). The counter style's algorithm is constructed by consulting the previous chapter using the provided system — or symbolic if the system was omitted — and the provided <string>s and <image>s as the value of the symbols property. If the system is fixed, the first symbol value is 1.

ol { list-style: symbols("*" "\2020" "\2021" "\A7"); }

*   One
†   Two
‡   Three
§   Four
**  Five
††  Six
‡‡  Seven

ol { list-style: symbols(cyclic "*" "\2020" "\2021" "\A7"); }

*   One
†   Two
‡   Three
§   Four
*   Five
†   Six
‡   Seven

Note: the symbols() function only allows strings and images, while the symbols descriptor of a @counter-style rule also allows identifiers.

5 Extending list-style-type, counter(), and counters()§

In CSS Level 2 [CSS21] the list-style-type property and the counter() and counters() notations accept various pre-defined keywords, each identifying a counter style. This module extends these features to take instead the <counter-style> type, defined below:

  <counter-style> = <counter-style-name> | symbols();

6 Simple Predefined Counter Styles§

The following stylesheet uses the @counter-style rule to redefine all of the counter styles defined in CSS 2 and CSS 2.1. This stylesheet is normative - UAs must include it in their UA stylesheet (or at least act as if these rules were defined at that level).

6.1 Numeric: decimal, decimal-leading-zero, cjk-decimal, lower-roman, upper-roman, armenian, georgian, hebrew§

decimal

Western decimal numbers (e.g., 1, 2, 3, ..., 98, 99, 100).

decimal-leading-zero

Decimal numbers padded by initial zeros (e.g., 01, 02, 03, ..., 98, 99, 100).

cjk-decimal

Han decimal numbers (e.g., 一, 二, 三, ..., 九八, 九九, 一〇〇).

lower-roman

Lowercase ASCII Roman numerals (e.g., i, ii, iii, ..., xcviii, xcix, c).

upper-roman

Uppercase ASCII Roman numerals (e.g., I, II, III, ..., XCVIII, XCIX, C).

armenian

Traditional uppercase Armenian numbering (e.g., Ա, Բ, Գ, ..., ՂԸ, ՂԹ, Ճ).

georgian

Traditional Georgian numbering (e.g., ა, ბ, გ, ..., ჟჱ, ჟთ, რ).

hebrew

Traditional Hebrew numbering (e.g., א‎, ב‎, ג‎, ..., צח‎, צט‎, ק‎).

The decimal counter-style must not be overridable with a @counter-style rule, so that it is always available as an ultimate fallback style.

The following stylesheet fragment provides the normative definition of these predefined counter styles:

@counter-style decimal {
  system: numeric;
  symbols: '0' '1' '2' '3' '4' '5' '6' '7' '8' '9';
}

@counter-style decimal-leading-zero {
  system: fixed -9;
  symbols: '-09' '-08' '-07' '-06' '-05' '-04' '-03' '-02' '-01' '00' '01' '02' '03' '04' '05' '06' '07' '08' '09';
}

@counter-style cjk-decimal {
  system: numeric;
  symbols: \3007  \4E00  \4E8C  \4E09  \56DB  \4E94  \516D  \4E03  \516B  \4E5D;
  /* 〇 一 二 三 四 五 六 七 八 九 */
  suffix: '\3001';
  /* "、" */
}

@counter-style lower-roman {
  system: additive;
  range: 1 4999;
  additive-symbols: 1000 m, 900 cm, 500 d, 400 cd, 100 c, 90 xc, 50 l, 40 xl, 10 x, 9 ix, 5 v, 4 iv, 1 i;
}

@counter-style upper-roman {
  system: additive;
  range: 1 4999;
  additive-symbols: 1000 M, 900 CM, 500 D, 400 CD, 100 C, 90 XC, 50 L, 40 XL, 10 X, 9 IX, 5 V, 4 IV, 1 I;
}

@counter-style armenian {
  system: additive;
  range: 1 9999;
  additive-symbols: 9000 \554, 8000 \553, 7000 \552, 6000 \551, 5000 \550, 4000 \54F, 3000 \54E, 2000 \54D, 1000 \54C, 900 \54B, 800 \54A, 700 \549, 600 \548, 500 \547, 400 \546, 300 \545, 200 \544, 100 \543, 90 \542, 80 \541, 70 \540, 60 \53F, 50 \53E, 40 \53D, 30 \53C, 20 \53B, 10 \53A, 9 \539, 8 \538, 7 \537, 6 \536, 5 \535, 4 \534, 3 \533, 2 \532, 1 \531;
  /* 9000 Ք, 8000 Փ, 7000 Ւ, 6000 Ց, 5000 Ր, 4000 Տ, 3000 Վ, 2000 Ս, 1000 Ռ, 900 Ջ, 800 Պ, 700 Չ, 600 Ո, 500 Շ, 400 Ն, 300 Յ, 200 Մ, 100 Ճ, 90 Ղ, 80 Ձ, 70 Հ, 60 Կ, 50 Ծ, 40 Խ, 30 Լ, 20 Ի, 10 Ժ, 9 Թ, 8 Ը, 7 Է, 6 Զ, 5 Ե, 4 Դ, 3 Գ, 2 Բ, 1 Ա */
}

@counter-style georgian {
  system: additive;
  range: 1 19999;
  additive-symbols: 10000 \10F5, 9000 \10F0, 8000 \10EF, 7000 \10F4, 6000 \10EE, 5000 \10ED, 4000 \10EC, 3000 \10EB, 2000 \10EA, 1000 \10E9, 900 \10E8, 800 \10E7, 700 \10E6, 600 \10E5, 500 \10E4, 400 \10F3, 300 \10E2, 200 \10E1, 100 \10E0, 90 \10DF, 80 \10DE, 70 \10DD, 60 \10F2, 50 \10DC, 40 \10DB, 30 \10DA, 20 \10D9, 10 \10D8, 9 \10D7, 8 \10F1, 7 \10D6, 6 \10D5, 5 \10D4, 4 \10D3, 3 \10D2, 2 \10D1, 1 \10D0;
  /* 10000 ჵ, 9000 ჰ, 8000 ჯ, 7000 ჴ, 6000 ხ, 5000 ჭ, 4000 წ, 3000 ძ, 2000 ც, 1000 ჩ, 900 შ, 800 ყ, 700 ღ, 600 ქ, 500 ფ, 400 ჳ, 300 ტ, 200 ს, 100 რ, 90 ჟ, 80 პ, 70 ო, 60 ჲ, 50 ნ, 40 მ, 30 ლ, 20 კ, 10 ი, 9 თ, 8 ჱ, 7 ზ, 6 ვ, 5 ე, 4 დ, 3 გ, 2 ბ, 1 ა */
}

@counter-style hebrew {
  system: additive;
  range: 1 infinite;
  additive-symbols: 400 \5EA, 300 \5E9, 200 \5E8, 100 \5E7, 90 \5E6, 80 \5E4, 70 \5E2, 60 \5E1, 50 \5E0, 40 \5DE, 30 \5DC, 20 \5DB, 19 \5D9\5D8, 18 \5D9\5D7, 17 \5D9\5D6, 16 \5D8\5D6, 15 \5D8\5D5, 10 \5D9, 9 \5D8, 8 \5D7, 7 \5D6, 6 \5D5, 5 \5D4, 4 \5D3, 3 \5D2, 2 \5D1, 1 \5D0;
  /* 400 ת, 300 ש, 200 ר, 100 ק, 90 צ, 80 פ, 70 ע, 60 ס, 50 נ, 40 מ, 30 ל, 20 כ, 19 יט, 18 יח, 17 יז, 16 טז, 15 טו, 10 י, 9 ט, 8 ח, 7 ז, 6 ו, 5 ה, 4 ד, 3 ג, 2 ב, 1 א */
  /* This system manually specifies the values for 19-15 to force the correct display of 15 and 16, which are commonly rewritten to avoid a close resemblance to the Tetragrammaton. */
}

6.2 Alphabetic: lower-alpha, lower-latin, upper-alpha, upper-latin, lower-greek, hiragana, hiragana-iroha, katakana, katakana-iroha§

lower-alpha

lower-latin

Lowercase ASCII letters (e.g., a, b, c, ..., z, aa, ab).

upper-alpha

upper-latin

Uppercase ASCII letters (e.g., A, B, C, ..., Z, AA, AB).

lower-greek

Lowercase classical Greek (e.g., α, β, γ, ..., ω, αα, αβ).

hiragana

Dictionary-order hiragana lettering (e.g., あ, い, う, ..., ん, ああ, あい).

hiragana-iroha

Iroha-order hiragana lettering (e.g., い, ろ, は, ..., ん, いい, いろ).

katakana

Dictionary-order katakana lettering (e.g., ア, イ, ウ, ..., ン, アア, アイ).

katakana-iroha

Iroha-order katakana lettering (e.g., イ, ロ, ハ, ..., ン, イイ, イロ)

The following stylesheet fragment provides the normative definition of these predefined counter styles:

@counter-style lower-alpha {
  system: alphabetic;
  symbols: a b c d e f g h i j k l m n o p q r s t u v w x y z;
}

@counter-style lower-latin {
  system: override lower-alpha;
}

@counter-style upper-alpha {
  system: alphabetic;
  symbols: A B C D E F G H I J K L M N O P Q R S T U V W X Y Z;
}

@counter-style upper-latin {
  system: override upper-alpha;
}

@counter-style lower-greek {
  system: alphabetic;
  symbols: \3B1  \3B2  \3B3  \3B4  \3B5  \3B6  \3B7  \3B8  \3B9  \3BA  \3BB  \3BC  \3BD  \3BE  \3BF  \3C0  \3C1  \3C3  \3C4  \3C5  \3C6  \3C7  \3C8  \3C9;
  /* α β γ δ ε ζ η θ ι κ λ μ ν ξ ο π ρ σ τ υ φ χ ψ ω */
}

@counter-style hiragana {
  system: alphabetic;
  symbols: \3042  \3044  \3046  \3048  \304A  \304B  \304D  \304F  \3051  \3053  \3055  \3057  \3059  \305B  \305D  \305F  \3061  \3064  \3066  \3068  \306A  \306B  \306C  \306D  \306E  \306F  \3072  \3075  \3078  \307B  \307E  \307F  \3080  \3081  \3082  \3084  \3086  \3088  \3089  \308A  \308B  \308C  \308D  \308F  \3092  \3093;
  /* あ い う え お か き く け こ さ し す せ そ た ち つ て と な に ぬ ね の は ひ ふ へ ほ ま み む め も や ゆ よ ら り る れ ろ わ を ん */
  suffix: '、';
}

@counter-style hiragana-iroha {
  system: alphabetic;
  symbols: \3044  \308D  \306F  \306B  \307B  \3078  \3068  \3061  \308A  \306C  \308B  \3092  \308F  \304B  \3088  \305F  \308C  \305D  \3064  \306D  \306A  \3089  \3080  \3046  \3090  \306E  \304A  \304F  \3084  \307E  \3051  \3075  \3053  \3048  \3066  \3042  \3055  \304D  \3086  \3081  \307F  \3057  \3091  \3072  \3082  \305B  \3059  \3093;
  /* い ろ は に ほ へ と ち り ぬ る を わ か よ た れ そ つ ね な ら む う ゐ の お く や ま け ふ こ え て あ さ き ゆ め み し ゑ ひ も せ す ん */
  suffix: '、';
}

@counter-style katakana {
  system: alphabetic;
  symbols: \30A2  \30A4  \30A6  \30A8  \30AA  \30AB  \30AD  \30AF  \30B1  \30B3  \30B5  \30B7  \30B9  \30BB  \30BD  \30BF  \30C1  \30C4  \30C6  \30C8  \30CA  \30CB  \30CC  \30CD  \30CE  \30CF  \30D2  \30D5  \30D8  \30DB  \30DE  \30DF  \30E0  \30E1  \30E2  \30E4  \30E6  \30E8  \30E9  \30EA  \30EB  \30EC  \30ED  \30EF  \30F2  \30F3;
  /* ア イ ウ エ オ カ キ ク ケ コ サ シ ス セ ソ タ チ ツ テ ト ナ ニ ヌ ネ ノ ハ ヒ フ ヘ ホ マ ミ ム メ モ ヤ ユ ヨ ラ リ ル レ ロ ワ ヲ ン */
  suffix: '、';
}

@counter-style katakana-iroha {
  system: alphabetic;
  symbols: \30A4  \30ED  \30CF  \30CB  \30DB  \30D8  \30C8  \30C1  \30EA  \30CC  \30EB  \30F2  \30EF  \30AB  \30E8  \30BF  \30EC  \30BD  \30C4  \30CD  \30CA  \30E9  \30E0  \30A6  \30F0  \30CE  \30AA  \30AF  \30E4  \30DE  \30B1  \30D5  \30B3  \30A8  \30C6  \30A2  \30B5  \30AD  \30E6  \30E1  \30DF  \30B7  \30F1  \30D2  \30E2  \30BB  \30B9  \30F3;
  /* イ ロ ハ ニ ホ ヘ ト チ リ ヌ ル ヲ ワ カ ヨ タ レ ソ ツ ネ ナ ラ ム ウ ヰ ノ オ ク ヤ マ ケ フ コ エ テ ア サ キ ユ メ ミ シ ヱ ヒ モ セ ス ン */
  suffix: '、';
}

6.3 Symbolic: disc, circle, square, disclosure-open, disclosure-closed§

disc

A filled circle, similar to • U+2022 BULLET.

circle

A hollow circle, similar to ◦ U+25E6 WHITE BULLET.

square

A filled square, similar to ◾ U+25FE BLACK MEDIUM SMALL SQUARE.

disclosure-open

disclosure-closed

Symbols appropriate for indicating an open or closed disclosure widget, such as the HTML <details> element.

The following stylesheet fragment provides the normative definition of these predefined counter styles:

@counter-style disc {
  system: cyclic;
  symbols: \2022;
  /* • */
  suffix: "";
}

@counter-style circle {
  system: cyclic;
  symbols: \25E6;
  /* ◦ */
  suffix: "";
}

@counter-style square {
  system: cyclic;
  symbols: \25FE;
  /* ◾ */
  suffix: "";
}

@counter-style disclosure-open {
  system: cyclic;
  suffix: "";
  /* for symbols, see normative text below */
}

@counter-style disclosure-closed {
  system: cyclic;
  suffix: "";
  /* for symbols, see normative text below */
}

Alternately, a browser may render these styles using a browser-generated image instead of the defined character. If so, the image must look similar to the character, and must be sized to attractively fill a 1em by 1em square.

For the disclosure-open and disclosure-closed counter styles, the marker must be an image or character suitable for indicating the open and closed states of a disclosure widget, such as HTML's <details> element. If the image is directional, it must respond to the writing mode of the element [CSS3-WRITING-MODES], similar to the bidi-sensitive images feature of the Images 4 module. For example, the disclosure-closed style might use the characters U+25B8 BLACK RIGHT-POINTING SMALL TRIANGLE (▸) and U+25C2 BLACK LEFT-POINTING SMALL TRIANGLE (◂), while the disclosure-open style might use the character U+25BE BLACK DOWN-POINTING SMALL TRIANGLE (▾).

7 Complex Predefined Counter Styles§

While authors may define their own counter styles using the @counter-style rule or rely on the set of predefined counter styles, a few counter styles are described by rules that are too complex to be captured by the predefined algorithms. These counter styles are described in this section.

Some of the counter styles specified in this section have custom algorithms for generating counter values, but are otherwise identical to a counter style defined via the @counter-style rule. For example, an author can reference one of these styles in an override system, reusing the algorithm but swapping out some of the other descriptors.

All of the counter styles defined in this section have a spoken form of numeric, and are all negative-capable.

7.1 Longhand East Asian Counter Styles: japanese-informal, japanese-formal, korean-hangul-formal, korean-hanja-informal, korean-hanja-formal, simp-chinese-informal, simp-chinese-formal, trad-chinese-informal, trad-chinese-formal§

Chinese, Japanese, and Korean have longhand counter styles, which have a structure similar to "one hundred thirteen thousand and twenty-three" in English. Each has both formal and informal variants. The formal styles are typically used in financial and legal documents, as their characters are more difficult to alter into each other.

japanese-informal

Informal Japanese Kanji numbering (e.g., 一万一千百十一)

japanese-formal

Formal Japanese Kanji numbering (e.g. 壱萬壱阡壱百壱拾壱)

korean-hangul-formal

Korean Hangul numbering (e.g., 일만 일천일백일십일)

korean-hanja-informal

Informal Korean Hanja numbering (e.g., 萬 一千百十一)

korean-hanja-formal

Forman Korean Han (Hanja) numbering (e.g., 壹萬 壹仟壹百壹拾壹)

simp-chinese-informal

Simplified Chinese informal numbering (e.g., 一万一千一百一十一)

simp-chinese-formal

Simplified Chinese formal numbering (e.g. 壹万壹仟壹佰壹拾壹)

trad-chinese-informal

Traditional Chinese informal numbering (e.g., 一萬一千一百一十一)

trad-chinese-formal

Traditional Chinese informal numbering (e.g., 壹萬壹仟壹佰壹拾壹)

cjk-ideographic

This counter style is identical to trad-chinese-informal. (It exists for legacy reasons.)

Note: The examples above show the number 11,111, which is not often used as a counter value, but illustrates the differences among the systems.

The Korean and Japanese variants of these counter styles can, if limited from 0 to 9999, be expressed as @counter-style rules. Thus, the implementation details are split into two sections: a required section defining the styles over this limited range, and an optional section defining them over a much larger range that requires custom algorithms for all of the styles.

7.1.1 Limited-range Implementation (required)§

Japanese§

@counter-style japanese-informal {
  system: additive;
  range: -9999 9999;
  additive-symbols: 9000 \4E5D\5343, 8000 \516B\5343, 7000 \4E03\5343, 6000 \516D\5343, 5000 \4E94\5343, 4000 \56DB\5343, 3000 \4E09\5343, 2000 \4E8C\5343, 1000 \5343, 900 \4E5D\767E, 800 \516B\767E, 700 \4E03\767E, 600 \516D\767E, 500 \4E94\767E, 400 \56DB\767E, 300 \4E09\767E, 200 \4E8C\767E, 100 \767E, 90 \4E5D\5341, 80 \516B\5341, 70 \4E03\5341, 60 \516D\5341, 50 \4E94\5341, 40 \56DB\5341, 30 \4E09\5341, 20 \4E8C\5341, 10 \5341, 9 \4E5D, 8 \516B, 7 \4E03, 6 \516D, 5 \4E94, 4 \56DB, 3 \4E09, 2 \4E8C, 1 \4E00, 0 \3007;
  /* 9000 九千, 8000 八千, 7000 七千, 6000 六千, 5000 五千, 4000 四千, 3000 三千, 2000 二千, 1000 千, 900 九百, 800 八百, 700 七百, 600 六百, 500 五百, 400 四百, 300 三百, 200 二百, 100 百, 90 九十, 80 八十, 70 七十, 60 六十, 50 五十, 40 四十, 30 三十, 20 二十, 10 十, 9 九, 8 八, 7 七, 6 六, 5 五, 4 四, 3 三, 2 二, 1 一, 0 〇 */
  suffix: '\3001';
  /* 、 */
  negative: "\30DE\30A4\30CA\30B9";
  /* マイナス */
  fallback: cjk-decimal;
}

@counter-style japanese-formal {
  system: additive;
  range: -9999 9999;
  additive-symbols: 9000 \4E5D\9621, 8000 \516B\9621, 7000 \4E03\9621, 6000 \516D\9621, 5000 \4F0D\9621, 4000 \56DB\9621, 3000 \53C2\9621, 2000 \5F10\9621, 1000 \58F1\9621, 900 \4E5D\767E, 800 \516B\767E, 700 \4E03\767E, 600 \516D\767E, 500 \4F0D\767E, 400 \56DB\767E, 300 \53C2\767E, 200 \5F10\767E, 100 \58F1\767E, 90 \4E5D\62FE, 80 \516B\62FE, 70 \4E03\62FE, 60 \516D\62FE, 50 \4F0D\62FE, 40 \56DB\62FE, 30 \53C2\62FE, 20 \5F10\62FE, 10 \58F1\62FE, 9 \4E5D, 8 \516B, 7 \4E03, 6 \516D, 5 \4F0D, 4 \56DB, 3 \53C2, 2 \5F10, 1 \58F1, 0 \96F6;
  /* 9000 九阡, 8000 八阡, 7000 七阡, 6000 六阡, 5000 伍阡, 4000 四阡, 3000 参阡, 2000 弐阡, 1000 壱阡, 900 九百, 800 八百, 700 七百, 600 六百, 500 伍百, 400 四百, 300 参百, 200 弐百, 100 壱百, 90 九拾, 80 八拾, 70 七拾, 60 六拾, 50 伍拾, 40 四拾, 30 参拾, 20 弐拾, 10 壱拾, 9 九, 8 八, 7 七, 6 六, 5 伍, 4 四, 3 参, 2 弐, 1 壱, 0 零 */
  suffix: '\3001';
  /* 、 */
  negative: "\30DE\30A4\30CA\30B9";
  /* マイナス */
  fallback: cjk-decimal;
}

Korean§

@counter-style korean-hangul-formal {
  system: additive;
  range: 0 9999;
  additive-symbols: 9000 \AD6C\CC9C, 8000 \D314\CC9C, 7000 \CE60\CC9C, 6000 \C721\CC9C, 5000 \C624\CC9C, 4000 \C0AC\CC9C, 3000 \C0BC\CC9C, 2000 \C774\CC9C, 1000 \C77C\CC9C, 900 \AD6C\BC31, 800 \D314\BC31, 700 \CE60\BC31, 600 \C721\BC31, 500 \C624\BC31, 400 \C0AC\BC31, 300 \C0BC\BC31, 200 \C774\BC31, 100 \C77C\BC31, 90 \AD6C\C2ED, 80 \D314\C2ED, 70 \CE60\C2ED, 60 \C721\C2ED, 50 \C624\C2ED, 40 \C0AC\C2ED, 30 \C0BC\C2ED, 20 \C774\C2ED, 10 \C77C\C2ED, 9 \AD6C, 8 \D314, 7 \CE60, 6 \C721, 5 \C624, 4 \C0AC, 3 \C0BC, 2 \C774, 1 \C77C, 0 \C601;
  /* 9000 구천, 8000 팔천, 7000 칠천, 6000 육천, 5000 오천, 4000 사천, 3000 삼천, 2000 이천, 1000 일천, 900 구백, 800 팔백, 700 칠백, 600 육백, 500 오백, 400 사백, 300 삼백, 200 이백, 100 일백, 90 구십, 80 팔십, 70 칠십, 60 육십, 50 오십, 40 사십, 30 삼십, 20 이십, 10 일십, 9 구, 8 팔, 7 칠, 6 육, 5 오, 4 사, 3 삼, 2 이, 1 일, 0 영 */
  suffix: '\3001';
  /* 、 */
}

@counter-style korean-hanja-informal {
  system: additive;
  range: 0 9999;
  additive-symbols: 9000 \4E5D\5343, 8000 \516B\5343, 7000 \4E03\5343, 6000 \516D\5343, 5000 \4E94\5343, 4000 \56DB\5343, 3000 \4E09\5343, 2000 \4E8C\5343, 1000 \5343, 900 \4E5D\767E, 800 \516B\767E, 700 \4E03\767E, 600 \516D\767E, 500 \4E94\767E, 400 \56DB\767E, 300 \4E09\767E, 200 \4E8C\767E, 100 \767E, 90 \4E5D\5341, 80 \516B\5341, 70 \4E03\5341, 60 \516D\5341, 50 \4E94\5341, 40 \56DB\5341, 30 \4E09\5341, 20 \4E8C\5341, 10 \5341, 9 \4E5D, 8 \516B, 7 \4E03, 6 \516D, 5 \4E94, 4 \56DB, 3 \4E09, 2 \4E8C, 1 \4E00, 0 \96F6;
  /* 9000 九千, 8000 八千, 7000 七千, 6000 六千, 5000 五千, 4000 四千, 3000 三千, 2000 二千, 1000 千, 900 九百, 800 八百, 700 七百, 600 六百, 500 五百, 400 四百, 300 三百, 200 二百, 100 百, 90 九十, 80 八十, 70 七十, 60 六十, 50 五十, 40 四十, 30 三十, 20 二十, 10 十, 9 九, 8 八, 7 七, 6 六, 5 五, 4 四, 3 三, 2 二, 1 一, 0 零 */
  suffix: '\3001';
  /* 、 */
}

@counter-style korean-hanja-formal {
  system: additive;
  range: 0 9999;
  additive-symbols: 9000 \4E5D\4EDF, 8000 \516B\4EDF, 7000 \4E03\4EDF, 6000 \516D\4EDF, 5000 \4E94\4EDF, 4000 \56DB\4EDF, 3000 \53C3\4EDF, 2000 \8CB3\4EDF, 1000 \58F9\4EDF, 900 \4E5D\767E, 800 \516B\767E, 700 \4E03\767E, 600 \516D\767E, 500 \4E94\767E, 400 \56DB\767E, 300 \53C3\767E, 200 \8CB3\767E, 100 \58F9\767E, 90 \4E5D\62FE, 80 \516B\62FE, 70 \4E03\62FE, 60 \516D\62FE, 50 \4E94\62FE, 40 \56DB\62FE, 30 \53C3\62FE, 20 \8CB3\62FE, 10 \58F9\62FE, 9 \4E5D, 8 \516B, 7 \4E03, 6 \516D, 5 \4E94, 4 \56DB, 3 \53C3, 2 \8CB3, 1 \58F9, 0 \96F6;
  /* 9000 九仟, 8000 八仟, 7000 七仟, 6000 六仟, 5000 五仟, 4000 四仟, 3000 參仟, 2000 貳仟, 1000 壹仟, 900 九百, 800 八百, 700 七百, 600 六百, 500 五百, 400 四百, 300 參百, 200 貳百, 100 壹百, 90 九拾, 80 八拾, 70 七拾, 60 六拾, 50 五拾, 40 四拾, 30 參拾, 20 貳拾, 10 壹拾, 9 九, 8 八, 7 七, 6 六, 5 五, 4 四, 3 參, 2 貳, 1 壹, 0 零 */
  suffix: '\3001';
  /* 、 */
}

Chinese§

The Chinese longhand styles are defined over the range -9999 to 9999. For numbers outside this range, the cjk-decimal style is used. All of the styles are defined by almost identical algorithms (specified as a single algorithm here, with the differences called out when relevant), but use different sets of characters. The list following the algorithm gives the name of each counter style using this algorithm, and the individual character sets used by each style.

1. If the counter value is 0, the representation is the character for 0 specified for the given counter style. Skip the rest of this algorithm.
2. Initially represent the counter value as a decimal number. For each digit that is not 0, append the appropriate digit marker to the digit. The ones digit has no marker.
3. For the informal styles, if the counter value is between ten and nineteen, remove the tens digit (leave the digit marker).
4. Drop any trailing zeros and collapse any remaining zeros into a single zero digit.
5. Replace the digits 0-9 with the appropriate character for the given counter style. Return the resultant string as the representation of the counter value.

For all of these counter styles, the suffix is "、" U+3001, the fallback is cjk-decimal, the range is -9999 9999, and the negative value is given in the table of symbols for each style.

The following tables define the characters used in these styles:

  1　　　　 一    41　　 四十一    81　　 八十一
  2　　　　 二    42　　 四十二    82　　 八十二
  3　　　　 三    43　　 四十三    83　　 八十三
  4　　　　 四    44　　 四十四    84　　 八十四
  5　　　　 五    45　　 四十五    85　　 八十五
  6　　　　 六    46　　 四十六    86　　 八十六
  7　　　　 七    47　　 四十七    87　　 八十七
  8　　　　 八    48　　 四十八    88　　 八十八
  9　　　　 九    49　　 四十九    89　　 八十九
 10　　　　 十    50　　　 五十    90　　　 九十
 11　　　 十一    51　　 五十一    91　　 九十一
 12　　　 十二    52　　 五十二    92　　 九十二
 13　　　 十三    53　　 五十三    93　　 九十三
 14　　　 十四    54　　 五十四    94　　 九十四
 15　　　 十五    55　　 五十五    95　　 九十五
 16　　　 十六    56　　 五十六    96　　 九十六
 17　　　 十七    57　　 五十七    97　　 九十七
 18　　　 十八    58　　 五十八    98　　 九十八
 19　　　 十九    59　　 五十九    99　　 九十九
 20　　　 二十    60　　　 六十   100　　　 一百
 21　　 二十一    61　　 六十一   101　 一百零一
 22　　 二十二    62　　 六十二   102　 一百零二
 23　　 二十三    63　　 六十三   103　 一百零三
 24　　 二十四    64　　 六十四   104　 一百零四
 25　　 二十五    65　　 六十五   105　 一百零五
 26　　 二十六    66　　 六十六   106　 一百零六
 27　　 二十七    67　　 六十七   107　 一百零七
 28　　 二十八    68　　 六十八   108　 一百零八
 29　　 二十九    69　　 六十九   109　 一百零九
 30　　　 三十    70　　　 七十   110　 一百一十
 31　　 三十一    71　　 七十一   111 一百一十一
 32　　 三十二    72　　 七十二   112 一百一十二
 33　　 三十三    73　　 七十三   113 一百一十三
 34　　 三十四    74　　 七十四   114 一百一十四
 35　　 三十五    75　　 七十五   115 一百一十五
 36　　 三十六    76　　 七十六   116 一百一十六
 37　　 三十七    77　　 七十七   117 一百一十七
 38　　 三十八    78　　 七十八   118 一百一十八
 39　　 三十九    79　　 七十九   119 一百一十九
 40　　　 四十    80　　　 八十   120　 一百二十

7.1.2 Extended Implementation (optional)§

Some counter styles described in earlier chapters have been limited to an artifically small (though still useful) range to reduce the overall complexity of the spec and the task of implementing those styles. However, some implementations might consider the extra complexity worthwhile for the additional range it offers to authors. To accomodate this, this section describes how to extend the limited counter-styles to a larger range.

This entire section is normative, but optional. User-agents may ignore it and still be conformant. If a user-agent implements some of the extended forms described in this section, they must be implemented as described here.

The Chinese longhand styles are defined out to 10k with a specialized algorithm, while the Japanese and Korean longhand styles are defined similarly as additive styles. However, these styles are defined out to 10¹⁶ in common usage. The following section describes an alternative algorithm for these styles.

The Chinese and Japanese styles are defined for all numbers between -10¹⁶ and 10¹⁶, exclusive; the Korean styles are defined for all non-negative numbers less than 10¹⁶. For numbers outside this range, the cjk-decimal style is used. All of the styles are defined by almost identical algorithms (specified as a single algorithm here, with the differences called out when relevant), but use different sets of characters. The list following the algorithm gives the name of each counter style using this algorithm, and the individual character sets used by each style.

1. If the counter value is 0, the representation is the character for 0 specified for the given counter style. Skip the rest of this algorithm.
2. Initially represent the counter value as a decimal number. Starting from the right (ones place), split the decimal number into groups of four digits.
3. For each group with a non-zero value, append the appropriate group marker to the group. The ones group has no marker.
4. Within each group, for each digit that is not 0, append the appropriate digit marker to the digit. The ones digit of each group has no marker.
5. Drop ones:
   • For the Chinese informal styles, for any group with a value between ten and nineteen, remove the tens digit (leave the digit marker).
   • For the Japanese informal and Korean informal styles, if any of the digit markers are preceded by the digit 1, and that digit is not the first digit of the group, remove the digit (leave the digit marker).
   • For Korean informal styles, if the value of the ten-thousands group is 1, drop the digit (leave the digit marker).
6. Drop zeros:
   • For the Japanese and Korean styles, drop all zero digits.
   • For the Chinese styles, drop any trailing zeros for all non-zero groups and collapse (across groups) each remaining consecutive group of zeros into a single zero digit.
7. For the Korean styles, insert a space (" " U+0020) between each group.
8. Replace the digits 0-9 with the appropriate character for the given counter style. Return the resultant string as the representation of the counter value.

For all of these counter styles, the suffix is "、" U+3001, the fallback is cjk-decimal, and the negative is given in the tables below, or else is the initial value of the descriptor. For Chinese and Japanese, the range is -9999999999999999 9999999999999999 (-10¹⁶+1 and 10¹⁶-1), while for Korean it's 0 9999999999999999 (again, 10¹⁶-1).

The following tables define the characters used in these styles:

7.2 Ethiopic Numeric Counter Style: ethiopic-numeric§

The ethiopic-numeric counter style is defined for all positive non-zero numbers. The following algorithm converts decimal digits to ethiopic numbers:

1. Split the number into groups of two digits, starting with the least significant decimal digit.
2. Index each group sequentially, starting from the least significant as group number zero.
3. If the group has an odd index (as given in the previous step) and has the value 1, or if the group is the most significant one and has the value 1, or if the group has the value zero, then remove the digit (but leave the group, so it still has a separator appended below).
4. For each remaining digit, substitute the relevant ethiopic character from the list below.

   Tens			Units
   Values	Codepoints		Values	Codepoints
   10	፲	U+1372	1	፩	U+1369
   20	፳	U+1373	2	፪	U+136A
   30	፴	U+1374	3	፫	U+136B
   40	፵	U+1375	4	፬	U+136C
   50	፶	U+1376	5	፭	U+136D
   60	፷	U+1377	6	፮	U+136E
   70	፸	U+1378	7	፯	U+136F
   80	፹	U+1379	8	፰	U+1370
   90	፺	U+137A	9	፱	U+1371

5. For each group with an odd index (as given in the second step) that did not have its digits removed in the third step, append ፻ U+137B.
6. For each group with an even index (as given in the second step), except the group with number 0, append ፼ U+137C.
7. Concatenate the groups into one string.

For this system, the name is "ethiopic-numeric", the range is 1 infinity, and the rest of the descriptors have their initial value.

Is there a better suffix to use than the initial (".")? The alphabetic ethiopic systems use a different suffix.

8 Additional Predefined Counter Styles§

The Internationalization Working Group maintains a large list of predefined @counter-style rules for various world languages in their Predefined Counter Styles document. These additional counter styles are not intended to be supported by user-agents by default, but can be used by users or authors copying them directly into style sheets.

9 APIs§

9.1 Extensions to the CSSRule interface§

The CSSRule interface is extended as follows:

partial interface CSSRule {
    const unsigned short COUNTER_STYLE_RULE = 11;
}

9.2 The CSSCounterStyleRule interface§

The CSSCounterStyleRule interface represents a @counter-style rule.

interface CSSCounterStyleRule : CSSRule {
  attribute DOMString name;
  attribute DOMString system;
  attribute DOMString symbols;
  attribute DOMString additiveSymbols;
  attribute DOMString negative;
  attribute DOMString prefix;
  attribute DOMString suffix;
  attribute DOMString range;
  attribute DOMString pad; 
  attribute DOMString fallback;
}

name of type DOMString

The name attribute on getting must return a DOMString object that contains the serialization of the <counter-style-name> defined for the associated rule.

On setting the name attribute, run the following steps:

1. Parse a component value from the value.
2. If the returned value is an 〈ident〉, replace the associated rule's name with the 〈ident〉's representation.
3. Otherwise, do nothing.

everything else

The remaining attributes on getting must return a DOMString object that contains the serialization of the associated descriptor defined for the associated rule.

On setting, run the following steps:

1. Parse a list of component values from the value.
2. If the returned value is valid according to the given descriptor's grammar, set that descriptor to the value.
3. Otherwise, do nothing.

10 Sample style sheet for HTML§

This section is informative, not normative. HTML itself defines the styles that apply to its elements, and in some cases defers to the user agent's discretion.

details > summary {
  display: list-item;
  list-style: disclosure-closed inside;
}

details[open] > summary {
  list-style: disclosure-open inside;
}

Changes since the Oct 2012 Working Draft§

• All counter systems can now handle negative values.
• The pad descriptor was added, to handle things like zero-padding integers.
• The speak-as descriptor was added, to control how generated counters should be spoken by speech UAs.
• The disclosure-open and disclosure-closed predefined list styles were added, for rendering the HTML <details> element.

Acknowledgments§

The following people and documentation they wrote were very useful for defining the numbering systems: Alexander Savenkov, Arron Eicholz, Aryeh Gregor, Christopher Hoess, Daniel Yacob, Frank Tang, Jonathan Rosenne, Karl Ove Hufthammer, Musheg Arakelyan, Nariné Renard Karapetyan, Randall Bart, Richard Ishida, Simon Montagu (Mozilla, [email protected])

Conformance§

Document conventions§

Conformance requirements are expressed with a combination of descriptive assertions and RFC 2119 terminology. The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in the normative parts of this document are to be interpreted as described in RFC 2119. However, for readability, these words do not appear in all uppercase letters in this specification.

All of the text of this specification is normative except sections explicitly marked as non-normative, examples, and notes. [RFC2119]

Examples in this specification are introduced with the words "for example" or are set apart from the normative text with class="example", like this:

Informative notes begin with the word "Note" and are set apart from the normative text with class="note", like this:

Note, this is an informative note.

Conformance classes§

Conformance to this specification is defined for three conformance classes:

style sheet

A CSS style sheet.

renderer

A UA that interprets the semantics of a style sheet and renders documents that use them.

authoring tool

A UA that writes a style sheet.

A style sheet is conformant to this specification if all of its statements that use syntax defined in this module are valid according to the generic CSS grammar and the individual grammars of each feature defined in this module.

A renderer is conformant to this specification if, in addition to interpreting the style sheet as defined by the appropriate specifications, it supports all the features defined by this specification by parsing them correctly and rendering the document accordingly. However, the inability of a UA to correctly render a document due to limitations of the device does not make the UA non-conformant. (For example, a UA is not required to render color on a monochrome monitor.)

An authoring tool is conformant to this specification if it writes style sheets that are syntactically correct according to the generic CSS grammar and the individual grammars of each feature in this module, and meet all other conformance requirements of style sheets as described in this module.

Partial implementations§

So that authors can exploit the forward-compatible parsing rules to assign fallback values, CSS renderers must treat as invalid (and ignore as appropriate) any at-rules, properties, property values, keywords, and other syntactic constructs for which they have no usable level of support. In particular, user agents must not selectively ignore unsupported component values and honor supported values in a single multi-value property declaration: if any value is considered invalid (as unsupported values must be), CSS requires that the entire declaration be ignored.

Experimental implementations§

To avoid clashes with future CSS features, the CSS2.1 specification reserves a prefixed syntax for proprietary and experimental extensions to CSS.

Prior to a specification reaching the Candidate Recommendation stage in the W3C process, all implementations of a CSS feature are considered experimental. The CSS Working Group recommends that implementations use a vendor-prefixed syntax for such features, including those in W3C Working Drafts. This avoids incompatibilities with future changes in the draft.

Non-experimental implementations§

Once a specification reaches the Candidate Recommendation stage, non-experimental implementations are possible, and implementors should release an unprefixed implementation of any CR-level feature they can demonstrate to be correctly implemented according to spec.

To establish and maintain the interoperability of CSS across implementations, the CSS Working Group requests that non-experimental CSS renderers submit an implementation report (and, if necessary, the testcases used for that implementation report) to the W3C before releasing an unprefixed implementation of any CSS features. Testcases submitted to W3C are subject to review and correction by the CSS Working Group.

Further information on submitting testcases and implementation reports can be found from on the CSS Working Group's website at http://www.w3.org/Style/CSS/Test/. Questions should be directed to the [email protected] mailing list.

References§

Normative References§

Informative References§

Index§

Property index§