To my knowledge, nobody has written a set of PHP include files to help with processing entire NWCTXT files, similar to the set that does exist to help with processing "clips" (the User Tools suite). Perhaps instead of writing a new suite, the existing one can become a superset for both? I haven't worked out all the details yet for other files, but I thought I'd throw out these possible additions to just nwc2clips.inc, to start a discussion.
In function NWC2ClassifyOptTag, before the final return:
if ($ObjType == "SongInfo") return NWC2OPT_TEXT;
if (($ObjType == "Font") && ($Tag == "Typeface")) return NWC2OPT_TEXT;
if (($ObjType == "AddStaff") && ($Tag == "Group")) return NWC2OPT_TEXT;
I expect there are other song/staff option tags that are possibly needed here too.
Global constants, alongside the comparable "clip" constants: