too much highlighting in compilation mode?

Can anybody explain to me the intention of the ***marked** line in the code fragment below? (defvar compilation-font-lock-keywords (purecopy (list '("^[-_.\"A-Za-z0-9/+]+\\(:\\|, line \\)[0-9]+: \\([wW]arning:\\).*$" . font-lock-keyword-face) '("^[-_.\"A-Za-z0-9/+]+\\(: *\\|, line \\)[0-9]+:.*$" . font-lock-function-name-face) ***'("^[^:\n]+-[a-zA-Z][^:\n]+$" . font-lock-doc-string-face)*** '("\\(^[-_.\"A-Za-z0-9/+]+\\)\\(: *\\|, line \\)[0-9]+" 1 font-lock-string-face t) '("^[-_.\"A-Za-z0-9/+]+\\(: *[0-9]+\\|, line [0-9]+\\)" 1 bold t) )) "Additional expressions to highlight in Compilation mode.") Seems to me that this winds up highlighting WAY too much stuff... pretty much any line with a hyphen in it, and no colons. It winds up giving ugly results - for instance, if you do a recursive make, and some directory names have hyphens, you get messages like Entering foo-bar getting highlighted, but messages like Entering baz are not, it just winds up looking inconsistent and random. I'd like to remove this piece of compilation-font-lock-keywords, but I'd like to understand why it's there, first.