Rational Developer for System z
Enterprise PL/I for z/OS, Version 3.8, Language Reference Manual

Identifiers

An identifier is a series of characters that are not contained in a comment or a constant. Except for P, PIC, and PICTURE, identifiers must be preceded and followed by a delimiter. (P, PIC, and PICTURE identifiers can be followed by a character string.) The first character of an identifier must be an alphabetic or extralingual character. If the identifier names an INTERNAL symbol, it may also use the break (_) character as its first character. Other characters, if any, can be alphabetic, extralingual, digit, or the break (_) character. External user names must not start with IBM, PLI, CEE, _IBM, _PLI, and _CEE.

Identifiers can be PL/I keywords or programmer-defined names. Because PL/I can determine from the context if an identifier is a keyword, you can use any identifier as a programmer-defined name. There are no reserved words in PL/I.

PL/I keywords

A keyword is an identifier that has a specific meaning in PL/I. Keywords can specify such things as the action to be taken or the attributes of data. For example, READ, DECIMAL, and ENDFILE are keywords. Some keywords can be abbreviated. The keywords and their abbreviations are shown in uppercase letters.

Programmer-defined names

In a PL/I program, names are given to variables and program-control data. There are also built-in names, condition names, and generic names. Any identifier can be used as a name. A name can have only one meaning in a program block; the same name cannot be used for both a file and a floating-point variable in the same block.

To improve readability, the break character (_) can be used in a name, such as Gross_Pay.

Examples of names are:

  A                   Rate_of_pay

  Record              Loop_3

Additional requirements for programmer-defined external names are given in INTERNAL and EXTERNAL attributes.

An asterisk (*) can be used as an identifier name in situations where a name is required but you do not otherwise refer to that identifier. For an example, see page ***.


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