http://gcc.gnu.org/install/specific.html#*-*-solaris2*

[Karl Berry]

    Now I now (and understand) that you changed the mangling of filenames,
    but where does the "g_t" come from, and why?

Catering to XHTML's stupidity.  I mentioned it in:

http://www.gnu.org/software/texinfo/manual/texinfo/texinfo.html#HTML-Xref-Link-Basics
viz.
    One exception: the algorithm for node name expansion prefixes the
    string `g_t' when the node name begins with a non-letter. This kludge
    (due to XHTML rules) is not necessary for filenames, and is
    therefore omitted.

Sorry ...