Appends the structures contained in caps2 to caps1 if they are not yet
expressed by caps1. The structures in caps2 are not copied -- they are
transferred to a writable copy of caps1, and then caps2 is freed.
If either caps is ANY, the resulting caps will be ANY.
Appends the structures contained in caps2 to caps1 if they are not yet expressed by caps1. The structures in caps2 are not copied -- they are transferred to a writable copy of caps1, and then caps2 is freed. If either caps is ANY, the resulting caps will be ANY.