Use shorter modifier names for slanted equal variants

[MDLC01]

Context

lt.eq.slant and gt.eq.slant are very long names for quite common symbols. It is also not immediately clear that the .slant modifier applies to the equal part of the symbol (lt.slant.eq and gt.slant.eq are equally valid, but ambiguous). For more context, see the discussion on Discord.

Similarly, prec.curly.eq (⪯) and succ.curly.eq (≽) make no sense.

In the following, I replace .eq.slant on lt and gt, and .curly.eq on prec and succ, with .seq. This is intended to be debated in this issue's comment thread.

Formal proposal

Rename four symbols from sym according to the following table.

Character	Current name	New name
⩽ LESS-THAN OR SLANTED EQUAL TO	lt.eq.slant	lt.seq
⩾ GREATER-THAN OR SLANTED EQUAL TO	gt.eq.slant	gt.seq
≼ PRECEDES OR EQUAL TO	prec.curly.eq	prec.seq
≽ SUCCEEDS OR EQUAL TO	succ.curly.eq	succ.seq

Breaking changes

lt.eq.slant and gt.eq.slant would become invalid.

Other information and concerns

Unicode defines the characters ⋞ EQUAL TO OR PRECEDES and ⋟ EQUAL TO OR SUCCEEDS, but no variant with a single horizontal line equal sign above ≺ or ≻. This may indicate that ≼ should be prec.eq, and ⪯ should be considered less common, and therefore use a more complex variant than plain eq (and similarly for ≽ and ⪰).

Concerns regarding this proposal were raised on Discord. Notably, "seq" reads like "sequence" and feels cryptic. A proposed solution is that the new names merely be added as aliases for those who wish to use them often, keeping the more self-describing names present as well.

Slanted variants of the parallel symbol use the .slanted modifier.

Related proposals

This proposal is incompatible with #43.

This proposal affects #36, since then prec.curly.eq would not be U+227C ≼ PRECEDES OR EQUAL TO, and succ.curly.eq would not be U+227D ≽ SUCCEEDS OR EQUAL TO.