This read-only INTEGER indicates whether the metric on this AS-External-LSA is a Type 2 external metric; when the value is on(2), bit E is set and the metric is Type 2 rather than Type 1. This distinction matters because OSPF always prefers external routes by internal cost first for Type 1 metrics, but compares Type 2 metrics directly regardless of internal distance to the ASBR. For example, this value set to on(2) tells the admin that OSPF will pick the external route with the lowest advertised metric even if it means routing through a more distant ASBR.