Kaushal Modi <kaushal.modi@gmail.com> writes:

> Subject: [PATCH] Document convention to reserve "p" or "-p" suffix for
>  predicate fns
>
> * doc/lispref/tips.texi (Coding Conventions): The "p" or "-p" suffix
>   should be used for only predicate functions, and not
>   variables.  (Bug#26564)

I've now applied this to Emacs 27.