I think you are right in that they are called braces (they are about
1.5 feet long). However, they are not connected to a purlin - they are
nailed to the sides of the rafters and joists.
The rafter span is only about 12 feet - SPF 2x8s, 16"c, 12/12 slope
will span over 15 feet here in the South. Why can't I remove the