What is the name of the language used to define the following syntax?

[ FROM {<table_source>} [,...n] ]

<join_type> ::=
[ INNER | { { LEFT | RIGHT | FULL } [OUTER]开发者_StackOverflow社区 } ]
[ <join_hint> ]
JOIN

Backus-Naur Form or the extended version?

It's called Backus-Naur form, although this looks like some non-standard variant. See http://en.wikipedia.org/wiki/Backus%E2%80%93Naur_Form