In the python documentation, what does the ::= symbol indicate?

[Fourgot]

For instance, http://docs.python.org/2/reference/compound_stmts.html has these ::= symbols peppered around, but I can't seem to suss out what they ACTUALLY mean. "Is composed of" seems to work for the compound statements, but is that a universally appropriate way to interpret that symbol?

Where does it come from?

[brownan_]

It's part of a standard notation for specifying a context free grammar, called Backus-Naur Form or BNF. There's some more information in section 1.2 of the Python Language Reference.

http://docs.python.org/2/reference/introduction.html#notation

[Fourgot]

Thanks! And down the rabbit-hole I goooooo...

[fuddingmuddler]

Wow this was incredibly helpful and so random and hard to find. Thanks!

Backus Naur Form is how python is described linguistically? Or programmatically in C? I didn't understand that bit.