Er, they didn't ommit anything. It's "protocol" : "location". The "//" is the base location in the hierarchy for the "http" and "ftp" protocols (among others).
":" is the single separator character, and not "://". See http://en.wikipedia.org/wiki/URI_scheme#Official_IANA-registered_schemes.
no subject
Date: 2010-05-27 19:12 (UTC)":" is the single separator character, and not "://". See http://en.wikipedia.org/wiki/URI_scheme#Official_IANA-registered_schemes.