- "Mode-specific function to apply the syntax-table properties.
-Called with two arguments: START and END.
-This function can call `syntax-ppss' on any position before END, but it
-should not call `syntax-ppss-flush-cache', which means that it should not
-call `syntax-ppss' on some position and later modify the buffer on some
-earlier position.")
+ "Mode-specific function to apply `syntax-table' text properties.
+It is the work horse of `syntax-propertize', which is called by things like
+Font-Lock and indentation.
+
+It is given two arguments, START and END: the start and end of the text to
+which `syntax-table' might need to be applied. Major modes can use this to
+override the buffer's syntax table for special syntactic constructs that
+cannot be handled just by the buffer's syntax-table.
+
+The specified function may call `syntax-ppss' on any position
+before END, but it should not call `syntax-ppss-flush-cache',
+which means that it should not call `syntax-ppss' on some
+position and later modify the buffer on some earlier position.")