license with patent grants appropriate for specifications?

[Bob Scheifler]

> Most robust open source licenses contain both copyright grants and patent
> grants. These licenses should be sufficient.

This goes to the heart of my original question. To be concrete,
if use the Apache License, Version 2.0 for a specification, and
I look at its grant of patent license, it covers patent claims
that are "necessarily infringed by the [specification]", it does
not explicitly cover patent claims that are necessarily infringed
by implementations of the specification. Am I correct in assuming
that a mere specification cannot directly infringe a patent claim?
(It may well be subject to claims of contributory infringement.)
In which case, the grant of patent license would seem to be
insufficient for enabling implementations. Or is there some other
existing open source license with more suitable grants? Looking at
AFL 2.1, perhaps "patent claims ... embodied in the [specification]"
is broad enough, but since the grant is only to "make, use, ... the
[specification] and Derivative Works", is that reasonably interpreted
as extending to implementations of the specification? And the AFL 2.1
termination provision appears to be limited to claims that the
"[specification] infringes a patent", so the same question about
whether a specification can directly infringe a patent arises.

- Bob