These constants define additional effects when drawing a text object.

Values:

IG_VECT_TXT_UNDERLINED	A text object is underlined.
IG_VECT_TXT_STRUCK	A text object is struck.
IG_VECT_TXT_DBLSTRUCK	A text object is double struck.
IG_VECT_TXT_SUPERSCRIPT	A text object is a superscript.
IG_VECT_TXT_SUBSCRIPT	A text object is a subscript.