There's reasonable documentation of the yield statement for most python versions under Section 6: Simple Statements, particularly 6.8 "The Yield Statement" (http://docs.python.org/release/2.7/reference/simple_stmts.html#the-yield-statement)

But, there's no mention of the return value of the yield statement, or that the send statement even exists.  It's mentioned in passing here under "PEP342 New Generator Features" (http://docs.python.org/whatsnew/2.5.html#pep-342-new-generator-features) but should be given fuller explanation and cross-linking from the yield statement documentation. 

It's also mentioned a bit here: http://docs.python.org/howto/functional.html#passing-values-into-a-generator but again, not under the language documentation itself.

okay, found the documentation I was looking for here:

http://docs.python.org/reference/expressions.html#yield-expressions

which appears to be copied and pasted and modified version of the docs here:

http://docs.python.org/reference/simple_stmts.html#grammar-token-yield_stmt

At the very least these should cross-reference each other, but I would guess that the text should be unified, but I'm not sure where.

Thanks for the report.  Are you interested in making a patch?  Guidelines are in the devguide.

The latest docs have a crossrefence at the end of the section:

http://docs.python.org/3/reference/simple_stmts.html#grammar-token-yield_stmt

I copied  the reference to 2.7 docs

New changeset 7b8c0bf8fcb8 by Andrew Kuchling in branch '2.7':
#14878: add cross-reference to the yield statement.
http://hg.python.org/cpython/rev/7b8c0bf8fcb8

Thanks for the patch!