TEX_DEFAULT:
A knob to choose teTeX or TeXLive. One can specify in /etc/make.conf.
USE_TEX:
A knob for port developers. Valid keywords are listed in
bsd.tex.mk.
KLatexFormula is a Qt4 program to easily get an image from a LaTeX
formula. Just enter a formula, click "Evaluate", then you can
drag&drop or copy the resulting image to another location (an
OpenOffice document, for example) or save it as an image (many
formats are available).
WWW: http://klatexformula.sourceforge.net