In #3559 (comment) we resolved to:

• adopt keyword based feature queries, with the expectation that we will use them rarely and test and message their addition carefully
• add a keyword for alignment on blocks

as proposed in #3559 (comment), with the names to be decided later.

As noted there, the names that I initially proposed were feature() and align-justify-properties-on-blocks. Other names for the keyword that were suggested during the discussion were align-content-on-block and align-content-block-flow.

What should we call these two things?