checkdoc-proper-noun-region-engine is a compiled Lisp function in `checkdoc.el'.

(checkdoc-proper-noun-region-engine BEGIN END)

Check all text between BEGIN and END for lower case proper nouns.
These are Emacs centric proper nouns which should be capitalized for
consistency. Return an error list if any are not fixed, but
internally skip over no answers.
If the offending word is in a piece of quoted text, then it is skipped.