This describes the specific kind of header fixup applied to this adjacency's encapsulation string when part of that header, such as an IP tunnel's outer header fields, can only be finalized at actual packet switch time rather than precomputed. This is the descriptive companion to the count in cefAdjSummaryFixup, so an admin who spots a nonzero fixup count can drill into this specific adjacency's object to see exactly what kind of per-packet header adjustment, such as tunnel IP header completion, is being performed. For an adjacency out of a GRE tunnel interface, this object would describe the fixup as completing the outer IP header's fields, such as length or checksum, that cannot be known until the actual packet is being switched.