Non-terminal symbol `SubTerm`

Defining rules for nonterminal symbol SubTerm:

`SubTerm`		`PsiTerm`
		`Feature` `ARROW` `PsiTerm`

Occurrences of symbol SubTerm in body of other rules:

`SubTerms`		`SubTerm`
`SubTerms`		`SubTerm` '`,`' `SubTerms`

Non-terminal symbol SubTerm