The 9 permission bits are divided into three groups of three bits each. The first group describes the permissions of the file owner, the second group describes the permissions of a group associated with the file owner or the directory containing the file, and the third group describes the permissions associated with any process which does not have the same user ID as the file. Each group of three bits contains a bit indicating the read, write or execute access is granted. In the case of directories, execute access is interpreted as the permission to perform a filename lookup within the directory.