polygen-spec_inc_abs.markdown

!comment

Appendix: Abstract syntax (EBNF Rules)
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This block is locale-agnostic and is commonly shared by all versions of
the Polygen Manual. Include it via the !include(FILENAME) PP macro.

!EBNF

S      ::= DECLS

DECL   ::= Nonterm "::=" PRODS
        |  Nonterm ":=" PRODS

DECLS  ::= (DECL ";")+

PRODS  ::= SEQ ("|" SEQ)*

SEQ    ::= [Label ":"] (ATOM)+

ATOM   ::= Nonterm
        |  Term
        |  "^"
        |  "_"
        |  "(" SUB ")"
        |  ATOM "."
        |  ATOM DotLabel

SUB ::= [DECLS] PRODS