If DC-ISIS is operating at both level 1 and level 2, this field indicates how DC-ISIS should decide whether to set the attached bit in its level 1 LSP. - 'attachNoOverlapOrRedist' indicates that the attached bit should be set if either of the following are true. - The IS can reach at least one other area (the IS is adjacent with a L2 router whose area addresses do not overlap with the area addresses we know about at L1). - The IS is redistributing one or more external routes into the AS. - 'attachNoOverlapOnly' indicates that the attached bit should be set only if the IS can reach at least one other area. - 'attachSet' indicates that the attached bit should always be set. - 'attachClear' indicates that the attached bit should never be set.