Assigning a prefix

To define a valid prefix that will not conflict with existing prefixes, adhere to the following guidelines:

Define a prefix as a 1- to 8-character string.
Do not use a prefix that is a command, an abbreviation of a command, or a command invocation; for example:
- "D" conflicts with MVS™ commands such as DISPLAY
- "$TP1,Q=A" conflicts with a command invocation.
Do not define a prefix that is either a subset or a superset of an existing prefix with the same first character. For example, if command prefix $XYZ already exists, command prefixes $, $X, and $XY are subsets of, and conflict with the original prefix. Similarly, prefixes $XYZ1 and $XYZ$ will also conflict with existing prefix $XYZ because they are supersets with the same first character. You can, however, define command prefixes XYZ, YZ, or Z, because they do not start with the same first character as the existing prefix. You can see which prefixes already exist by issuing the DISPLAY OPDATA command.
Define a prefix using characters from the set of valid characters listed in Table 1. This list is not exhaustive as the CPF macro will allow any hex value from X'41' to X'FE'.

Table 1. Valid Character Set
Character Set	Contents
Alphanumeric	alphabetic numeric	Uppercase A through Z 0 through 9
National (See note)	“at” sign dollar sign pound sign	@, $, # (Characters that can be represented by hexadecimal values X'7C', X'5B', and X'7B')
Special	comma, period, slash, apostrophe, left parenthesis, right parenthesis, asterisk, ampersand, plus sign, hyphen, equal sign, cent sign, less than sign, vertical bar, exclamation point, semi-colon, percent sign, underscore, greater than sign, question mark, colon, quotation marks	, . / ' ( ) * & + - = ¢ < \| ! ; % _ > ? : "

Note: The system recognizes the following hexadecimal representations of the U.S. National characters: @ as X'7C', $ as X'5B', and # as X'7B'. In countries other than the U.S., the U.S. National characters represented on terminal keyboards might generate a different hexadecimal representation and cause an error. For example, in some countries the $ character may generate a X'4A'.