I'm working on a font, and I'm using Microsoft Volt to apply ligatures and OpenType features. I have a glyph for the word "the", but I only want it to apply if it's used as a standalone word. For example, I only want the ligature to kick in when I type the word "the" by itself. If I type "these" or "brother", I want it to revert to the "th" ligature (the way it's drawn, it looks weird with a letter after the "the" ligature). Is there any way to do this? I played around with the order of the ligatures, but nothing seems to work. I considered including the space glyph in the ligature, but then I'd have to type the space bar twice after every "the" and that would be stupid. Any ideas? Or does this require a different typographical feature other than <liga>?

It's a multiple substitution.

http://www.adobe.com/devnet/opentype/afdko/topic_feature_file_syntax.html#5

I am sorry. I do not use Volt.