;
; authority from the URI RFC 3986
; NOTE: While we have greatly simplified "userinfo" and "host",
;       the simplifications retain the fact that there is a great
;       deal of overlap in the characters space accepted by the two phrases.
;       That is, "userinfo" and "host" could easily both accept the same phrase.
;       And that is the essential problem this grammar is designed to emphasize.
;
authority     = [ userinfo "@" ] host [ ":" port ]
host          = reg-name
;userinfo      = *( unreserved / pct-encoded / sub-delims / ":" )
;host          = IP-literal / IPv4address / reg-name
;reg-name      = *( unreserved / pct-encoded / sub-delims )
userinfo      = *( ALPHA / DIGIT / "." / ":" )
reg-name      = *( ALPHA / DIGIT/ "." )
port          = *DIGIT
ALPHA         = %d65-90 / %d97-122
DIGIT         = %d48-57