SVR4 permits supplementary code set characters in names where POSIX would prohibit them.

supplementary code set - the portion of the code set not included in the portable filename character set.

supplementary code set character - character from the supplementary code set.

In SVR4, supplementary code set characters are not permitted in: Process ID numbers, message queue, semaphore, and shared memory identifiers, external symbol names and fill patterns for cc and as commands, and layer names.

In SVR4, supplementary code set characters are permitted, but not encouraged in: user names, group names, passwords, names of devices, terminals, and special devices, printer names and printer class names, system names, disk pack, diskette, and tape label/volume names, RFS resource names, environment variable names.

In SVR4, supplementary code set characters are permitted in: filenames, directory names, command names, file system names.