;
; SABNF grammar for parsing out the replacement string parameters
;
rule = *(*any-other [(escape / match / prefix/ suffix/ xname / error)])
error = "$" any-other
escape = "$$"
match  = "$&"
prefix = "$`"
suffix = "$'"
xname = "${" name "}"
name = alpha *(alpha/digit/%d45/%d95)
alpha = %d97-122 / %d65-90
digit = %d48-57
any-other = %x20-23 / %x25-FFFF / %xA-D