XL Fortran for AIX 8.1

Language Reference


A Fortran statement is a sequence of lexical tokens. Statements are used to form program units.

+-------------------------------IBM Extension--------------------------------+

The maximum length of a statement in XL Fortran is 6700 characters.

+----------------------------End of IBM Extension----------------------------+

See Part 3, Statements and Directives of this book for details on all statements supported by XL Fortran.

Statement Keywords

A statement keyword is part of the syntax of a statement, and appears in uppercase bold everywhere but in syntax diagrams and tables. For example, the term DATA in the DATA statement is a statement keyword.

No sequence of characters is reserved in all contexts. A statement keyword is interpreted as an entity name if the keyword is used in such a context.

Statement Labels

A statement label is a sequence of one to five digits, one of which must be nonzero, that you can use to identify statements in a Fortran scoping unit. In fixed source form, a statement label can appear anywhere in columns 1 through 5 of the initial line of the statement. In free source form, such column restrictions do not apply.

+-------------------------------IBM Extension--------------------------------+

XL Fortran ignores all characters that appear in columns 1 through 5 on fixed source form continuation lines.

+----------------------------End of IBM Extension----------------------------+

Giving the same label to more than one statement in a scoping unit will cause ambiguity, and the compiler will generate an error. White space and leading zeros are not significant in distinguishing between statement labels. You can label any statement, but statement labels can only refer to executable statements and FORMAT statements. The statement making the reference and the statement it references (identified by the statement label) must be in the same scoping unit in order for the reference to resolve. (See Scope for details).

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