'(?:'.
'(?:'. //Known protocols
'(?:'.
- '(?:(?:https?|ftps?|mms|rtsp|gopher|news|nntp|telnet|wais|file|prospero|webcal|irc)://)'.
+ '(?:(?:https?|ftps?|mms|rtsp|gopher|news|nntp|telnet|wais|file|prospero|webcal|ircs?)://)'.
'|'.
'(?:(?:mailto|aim|tel|xmpp):)'.
')'.