Pg. of GC20-1819-2 Rev March 30, 1979 by Supp. SD23-9024-1 for 5748-XX8 DISK LOGICAL BLOCK SIZE II£.§ 2314 21 11 5 3330-11 149 86 44 3340 50 26 11 3350 45 25 13 3310 55 29 15 3370 216 114 59
How eMS Files Get Their Names When you create a CMS file, you can give it any filename and filetype
you wish. rules for forming filenames and filetypes are: • The filename and filetype can each be from one to eight characters. • The valid characters are A-Z, 0-9, and $, I, a. When you enter a command line into the VM/370 system, VM/370 always
translates your input line into uppercase characters. So, when you
specify a file identifier, you can enter it in lowercase.
Remember that, by default, the t and m characters are line editing symbols in VM/370i when you use them to identify a file, you must
precede them with the logical escape symbol (").
The third field in the file identifier, the filemode, indicates the
mode letter (A-Z) currently assigned to the virtual disk on which you
want the file to reside. When you use the CMS editor to create a file,
and you do not specify this field, the file you create is written on
your A-disk, and has a filemode letter of A.
The filemode letter, for any file, can change during a terminal
session. For example, when you log on, your virtual disk at address 191
is accessed as your A-disk, so a file on that disk named SPECIAL EVENTS has a file identifier of: SPECIAL EVENTS A
If, however, you later access another disk as your A-disk, and access
your 191 as your B-disk, then this file has a file identifier of: SPECIAL EVENTS B DUPLICATING FILENAMES AND FILETYPES You can give the same filename to as many files on a given disk as you
want, as long as you assign them different filetypes. Or you can create
many files with the same filetype but different filenames.
For the most part, filenames that you choose for your files have no
special significance to CMS. If, however, you choose a name that is the same as the name of a CMS command, and the file that you assign this
name to is an executable module or EXEC procedure, then you may encounter difficulty if you try to execute the CMS command whose name
you duplicated.
44 IBM VM/370 CMS User's Guide

Pg. of GC20-1819-2 Rev March 30, 1979 by SUppa SD23-9024-1 for 5748-118 For an explanation of how CMS id.ntifies a command namS, see "CftS Command Search Order" later in this section. Many CMS commands allow you to specify one or more of the fields in a
file identifier as an asterisk (*) or equal sign (=), which identify
files with similar fileids. Some CMS commands that manipulate disk files allOW you to enter the filename and/or filetype fields as an asterisk (*), indicating that all
files of the specified filename/filetype are to be mOdified. These
commands are: COPYFILE ERASE RENAME TAPE DUMP For example, if you specify:
erase * test a
all files with a filetype of TEST on your A-disk are erased.
Section 4. The CftS File System 44.1