Generic Syntax for URI (RFC 3986) — URI Authority

[ userinfo  "@" ]   host   [ ":"  port ]

*( unreserved /  pct‑encoded /  sub‑delims /  ":" )

IP-literal /  IPv4address /  reg‑name

"["  ( IPv6address /  IPv6addrz /  IPvFuture )  "]"

IPv6address  "%25"  ZoneID  ; see   RFC 6874

1*( unreserved /  pct‑encoded )

"v"  1*HEXDIG  "."  1*( unreserved /  sub‑delims /  ":" )

6( h16  ":" )  ls32  /
"::"  5( h16  ":" )  ls32  /
[ h16 ]  "::"  4( h16  ":" )  ls32  /
[ *1( h16  ":" )  h16 ]  "::"  3( h16  ":" )  ls32  /
[ *2( h16  ":" )  h16 ]  "::"  2( h16  ":" )  ls32  /
[ *3( h16  ":" )  h16 ]  "::"  h16  ":"    ls32  /
[ *4( h16  ":" )  h16 ]  "::"  ls32  /
[ *5( h16  ":" )  h16 ]  "::"  h16  /
[ *6( h16  ":" )  h16 ]  "::"

( h16   ":"   h16 ) /  IPv4address

1*4HEXDIG

dec-octet  "."  dec-octet  "."  dec-octet  "."  dec-octet

DIGIT  /     ; 0-9
%x31-39   DIGIT  /     ; 10‑99
"1"  2DIGIT  /     ; 100‑199
"2"  %x30‑34   DIGIT  /     ; 200‑249
"25"  %x30‑35     ; 250‑255

*( unreserved /  pct‑encoded /  sub‑delims )

*DIGIT