This read-create integer is a bit vector of administrative-group colors that must be absent from every link this path traverses, meaning the intersection of a candidate link's colors and this exclude set must be null for the link to be usable. It lets an administrator steer a tunnel's path computation away from links carrying undesirable attributes, such as a shared or unreliable segment. An operator wanting a tunnel to avoid a specific unreliable microwave hop tagged with a given color would set csMplsPathExclude to that color's bit, forcing path computation around it.