"Comment Subject" and "Comment Reference" styles

In Word 2003, I can't figure out what these styles are used for. I've
modified them both to see if I could figure out what changed, but nothing
changed.

1. What are these two styles used for?

2. Also, the text inside my comment balloons appears as "Comment [om]: my
comment...." What style does word use for the "Comment [om]" part? (It does
not seem to be either the Comment Subject or Comment Reference style, because
I've tried modifying those styles, and nothing changes inside the comment
balloon.

Thanks.