Rules for Control-List Parameters

Control-list parameters can be specified in the following forms:

Keyword Form: In this form, the control list parameter is specified by using a keyword and equal sign. Control-list parameters using keyword form can appear in any order in the control list.
Nonkeyword Form: In this form, the control-list parameter is specified without a keyword or equal sign. Either the logical unit specifier or the internal file specifier must occupy the first (leftmost) position in the control list.
The nonkeyword form of the direct-access record specifier must immediately follow the nonkeyword form of the logical unit specifier.
When used with a logical unit specifier or internal file specifier, the nonkeyword form of the format or namelist specifier must occupy the second position in the control list. The unit or internal file specifier must also be in nonkeyword form (and occupy the first position in the control list).
Mixed Form: In this form, keyword and nonkeyword forms are mixed in the same I/O statement. Control-list parameters using mixed form must follow nonkeyword form rules.