help-xref-symbol-regexp

help-xref-symbol-regexp is a variable defined in `help-mode.el'.
Its value is

"\\(\\<\\(\\(variable\\|option\\)\\|\\(function\\|command\\|call\\)\\|\\(face\\)\\|\\(symbol\\|program\\|property\\)\\|\\(source \\(?:code \\)?\\(?:of\\|for\\)\\)\\)[ 	\n]+\\)?`\\(\\sw\\(\\sw\\|\\s_\\)+\\)'"

• This variable may be risky if used as a file-local variable.

Documentation:
Regexp matching doc string references to symbols.

The words preceding the quoted symbol can be used in doc strings to
distinguish references to variables, functions and symbols.