font-lock-syntactic-keywords

font-lock-syntactic-keywords is a variable defined in `font-lock.el'.
Its value is

nil

• This variable is obsolete since 24.1;
  use `syntax-propertize-function' instead.
• This variable may be risky if used as a file-local variable.

Documentation:
A list of the syntactic keywords to put syntax properties on.
The value can be the list itself, or the name of a function or variable
whose value is the list.

See `font-lock-keywords' for a description of the form of this list;
only the differences are stated here. MATCH-HIGHLIGHT should be of the form:

(SUBEXP SYNTAX OVERRIDE LAXMATCH)

where SYNTAX can be a string (as taken by `modify-syntax-entry'), a syntax
table, a cons cell (as returned by `string-to-syntax') or an expression whose
value is such a form. OVERRIDE cannot be `prepend' or `append'.

Here are two examples of elements of `font-lock-syntactic-keywords'
and what they do:

("\\$\\(#\\)" 1 ".")

gives a hash character punctuation syntax (".") when following a
dollar-sign character. Hash characters in other contexts will still
follow whatever the syntax table says about the hash character.

("\\('\\).\\('\\)"
(1 "\"")
(2 "\""))

gives a pair single-quotes, which surround a single character, a SYNTAX of
"\"" (meaning string quote syntax). Single-quote characters in other
contexts will not be affected.

This is normally set via `font-lock-defaults'.