During phase 1, fsck(1M) found that the specified inode was neither allocated nor unallocated. The reason is probably that the system crashed in the middle of a sync(2) or write(2) operation.
Should you answer yes to this question, "UNALLOCATED" messages might result during phase 2, if any directory entries point to this inode. If you are being careful, exit fsck(1M) and run ncheck(1M) (specifying the inode number after the -i option) to determine which file or directory is involved here. You might be able restore this file or directory from another system. It is also possible that fsck(1M) will copy this file to the lost+found directory in a later phase.
For more information, see the chapter on checking filesystem integrity in the System Administration Guide, Volume I.