bnf.wsn

syntax         = rule [ syntax ] .
rule           = "<" rule-name ">" "::="
                 expression line-end .
expression     = list [ "|" expression ] .
line-end       = EOL | line-end line-end .
list           = term [ list ] .
term           = literal | "<" rule-name ">" .
literal        = """" text """" | "'" text "'" .