How CMS Files Get Their Names

When you create a CMS file, you can give it any file name and file type you wish. The rules for forming file names and file types are:
  • The file name and file type can each be from one to eight characters.
  • The valid characters are A-Z, a-z, 0-9, $ (dollar sign), # (pound sign), @ (at sign), + (plus sign), - (hyphen), : (colon), and _ (underscore).
    Note: Lowercase letters within a file ID are valid for use within the CMS file system. However, some CMS commands do not support file IDs that contain lowercase letters.

When you enter a command into the z/VM system, z/VM translates your input line by either the user-defined input table or by the uppercase table. For more information on the SET INPUT command, see z/VM: CMS Commands and Utilities Reference. If you do not have an input table, you can just enter the command in lowercase and z/VM translates your input line into uppercase characters.

Note: When defining input characters be sure that you will not end up with a file ID containing unsupported characters.

The @ and @ characters are line editing symbols in z/VM; when you use them to identify a file, you must precede them with the logical escape symbol ("). For more information on logical line editing symbols, see z/VM: CP Commands and Utilities Reference.

The third field in the file identifier is either the file mode (fm) or the directory name (dirname). The first character of a directory name can be an uppercase or lowercase letter (A-Z), a number (0-9), or one of several special characters, $ (dollar sign), # (pound sign), @ (at sign), - (hyphen), or _ (underscore). The remaining characters can be A-Z and 0-9. Lowercase letters are allowed, as they are translated to uppercase. For more information about directory names, see Using the Shared File System and z/VM: CMS Commands and Utilities Reference.

The file mode is made up of:

File Mode Description
Letter Specifies an alphabetic character (A-Z) currently assigned to the SFS directory or minidisk where you want the file to reside. When you use the editor to create a file, and you do not specify this field, the file you create is written to the directory or minidisk accessed with a file mode of A.
The file mode letter, for any file, can change during a terminal session. Suppose when you log on, your top directory (or minidisk) is accessed with a file mode of A. (Your top directory is the directory assigned to you by the SFS administrator at the time you are enrolled in a file pool.) A file in that directory (or minidisk), named SPECIAL EVENTS, would have a file identifier of: 
SPECIAL EVENTS A
If, however, you later access another directory (or minidisk) with a file mode of A, and access your top directory (or minidisk) with a file mode of B, then the SPECIAL EVENTS file will have a file identifier of: 
SPECIAL EVENTS B
Number Specifies a number from 0 to 6. Each number has a particular meaning to CMS. For more information, see File Mode Letters and Numbers.