This site describes solve-engine 2.44.0, the version npm installs.
TAGS_PACKAGE
const TAGS_PACKAGE: IEnginePackage;Defined in: packages/engine/src/packages/tags/TagsPackage.ts:31
Category tag sums: a mid-line #tag annotates a data line, and total of #tag / sum of #tag / average of #tag / count of #tag collect every line
in the document carrying that tag, across the non-adjacent lines that
total above and the table-column aggregates cannot reach. total by tag
breaks the whole note down by every tag at once, each with its share.
Collision-safety (this codebase’s phrase-fusion-not-bare-keyword policy): the
#tag token is claimed in the lexer only for a # directly followed by a
letter mid-line, so # (space) and // stay free-text comments and a
line-start # stays a heading. The aggregate triggers reuse the math-phrase
fusions (total of, count of, average of) and the raw sum of, and the
breakdown needs all of total by tag, so bare total/sum/count/average
and tag never become keywords and :total = 5 is untouched.