Attributes are considered distinct from other metadata, such as dates and times, filename extensions or file system permissions.
[11] In Unix and Unix-like systems, including POSIX-conforming systems, each file has a 'mode' containing 9 bit flags controlling read, write and execute permission for each of the file's owner, group and all other users (see File-system permissions §Traditional Unix permissions for more details) plus the setuid and setgid bit flags and a 'sticky' bit flag.
Prevents any change to file's contents or metadata: file/directory cannot be written to, deleted, renamed, or hard-linked.
[19] It has been carried forward from there into both the Oracle Solaris 11 releases and the open source illumos project.
Prevents any change to file's contents or metadata (except access time): file/directory cannot be written to, deleted, or renamed.