t is for "term" (semi-standard parsing terminology when using rules to determine precedence - usually there are more of those, including e.g. "factor" for multiplication).
v=verb (one), e=expression (one) V=verbs (jone or many, uxtaposed), N = nouns (one or many, juxtaposed), A = adverbs (one or many), E = expression list, semicolon separated, so "E:E;e|e" means: "A list of expressions is either: (a) a list of expressions, followed by semicolon, followed by one expression - or (b) just one expression"
It's recursive in a way that doesn't "seem right" if you're not used to it, but it IS well defined, and many parser generators know how to deal with it. In practice, if you're writing the parser by hand, you'd implement it as "parse the e first; then while (there's a semicolon next) do (parse another e).
