So what, exactly, is an art writing pen?

[snickersnack]

And where can I find one? dd's new preschool requires me to embroider her name on the front of the smock-type thing, or write it in "art writing pen". I can't sew so the art writing pen it is...but I can't see any such thing when I google it.

Don't know but if you go to Hobbycraft or any good craft shop you should be able to find permanent fabric writing pens. In big craft shops they should have several nice colours, so what you lack in sewing skill you could make up for in artistic flair!