Because SCLM macros are S/370 Assembler macros, all rules pertaining to Assembler macros apply to them. You can find more information on Assembler macros in the HLASM Language Reference.

These additional SCLM guidelines apply to the use of SCLM macros:

• Assembler does not support blanks in macro parameters. If a blank is used in a parameter that is delimited by parentheses, everything on the line after the blank will be ignored. If you use single quotes to delimit parameters, be careful when continuing to a new line. All blanks between the first single quote and the continuation character are considered part of the parameter. This can result in exceeding the maximum parameter length. If you need more than 71 characters for a line of code, you must put a continuation character in column 72 and begin the remaining lines in column 16.
• The maximum length of a parameter is 255 characters. (This is the maximum length of an Assembler macro call operand.)
• If any commas are omitted from the parameter list for any of the macros, the project definition might assemble correctly, but SCLM might use different defaults than expected, resulting in errors. All parameters except the last must be followed by a comma.
• If an optional parameter is specified without a value or the parameter is not specified, the default value is used; for example, PARM2A= or not specifying PARM2A on the macro statement causes PARM2A to default to Y. If the parameter does not have a default value then no value (null) is specified for the parameter.
• SCLM handles invalid values for required and optional parameters differently. If you specify an invalid value for a required parameter, SCLM might issue an error message and the project definition assembly ends with a return code of 8. If you specify an invalid value for an optional parameter, SCLM issues a warning message, uses the default value for the parameter, and returns a return code of 4. Limited verification of the parameters is done during the assembly of the project definition. In many cases, the error does not occur until run time. An MNOTE is added to the assembly listing to indicate the invalid parameter specifications.
• SCLM performs validation of data set names when the data sets are opened. SCLM performs validation of VSAM versioning data set names when they are required for use by SCLM.
• The messages you receive when the project definition is assembled are issued from the SCLM macros and the assembler. SCLM messages are identified as MNOTEs. For more information, refer to "SCLM macro messages (MNOTEs)" in z/OS ISPF Messages and Codes. For explanations of other messages, refer to the HLASM Programmer's Guide.
  The SCLM MNOTEs appear in one of two places within the listing:

  • Directly after the SCLM macro statement that contains incorrect parameter values
  • Near the end of the listing where SCLM cross-checks the values of the various SCLM macro statements. Assembler error messages usually occur inline where the syntax error was made.