4. CA MICS Facilities › 4.3 User Exit Facilities › 4.3.1 Definition and Methodology

4.3.1 Definition and Methodology

CA MICS exit points are provided to permit the addition of
user code at key points in the execution of CA MICS.

Within CA MICS, you may implement user code which is to be
used throughout all database units in the CA MICS database
complex, or you may selectively implement code to be used by
a single database unit only.  Your careful attention to the
structure of the CA MICS complex libraries and the exit
routines will assure the successful operation of your code.

The text in the following sections makes many references
to SAS language macro processing.  All references to SAS
macro processing use the same terminology.

  o  The term "SAS Macro Statement" is used to refer to the
     macros in use before SAS Version 82, which were coded in
     the form

          MACRO name ...content... %

  o  The term "SAS Macro Language" is used to refer to the
     macro language delivered with current levels of SAS.
     This language includes both %MACRO constructions and
     global variables.  These are constructed in the form

          %MACRO name;
              ...content...
          %MEND name;

     or

          %LET name = ...content... ;

  o  The term "SAS Macro" without the reference to statement
     or language is used to refer to the concept of inserting
     variable code into CA MICS programs.

    The DOs and DON'Ts below remind you about SAS coding
techniques.

              ****  D O   the following:  ****


     DO:  Use a double percent sign (%%) when attempting to
          code a single percent sign within a SAS Macro
          Statement (but not with SAS Macro Language).  SAS
          senses this inside macro code and converts the
          compiled constant to a single %.

     DO:  Use the member supplied in the distributed version
          of the prefix.MICS.USER.SOURCE library as the
          starting point for your database unit local exits.

     DO:  Use the member supplied in the distributed version
          of the sharedprefix.MICS.SOURCE library as the
          starting point for your complex-wide exits.

     DO:  Liberally comment all code.

     DO:  Examine input record length to be sure INPUT
          requests can be satisfied from the current record.

     DO:  Reference input field locations with pointer logic
          where possible.

     DO:  Preserve data element integrity by type (numeric,
          time stamp, character variable) and range (having
          the value agree with the FORMAT and LENGTH
          specifications).

     DO:  Define new retained data elements by specifying
          the RETAIN statement after LENGTH and FORMAT
          statements, if applicable.

     DO:  Test all exit logic under the CA MICS-required SAS
          release BEFORE implementation into production.

     DO:  Call the CA MICS Product Support Group if you have
          ANY questions.

             ****   D O N ' T   do the following:  ****


     DON'T:  Define SAS macros in your exit code. SAS will
             not allow a macro to be defined within a SAS
             macro statement definition.

     DON'T:  Use columns 73-80 for SAS statements. CA MICS
             uses only 1-72.

     DON'T:  Code these SAS statements in your exit:  RETURN,
             DELETE, or INPUT without a trailing '@'.

     DON'T:  Code INPUT statements that could cause SAS
             to perform an automatic input statement skip.
             Use the RECLEN variable to be sure the record is
             big enough to contain data at any intended input
             offset.

     DON'T:  Forget the CA MICS naming standards, especially
             for DDnames, file names, and data element file
             prefixes.

     DON'T:  Assume that any data element is RETAINed or
             not RETAINed.

     DON'T:  Redefine any currently existing CA MICS data
             element unless the documentation of the specific
             exit in question says it is allowed.

     DON'T:  Assume that the SAS automatic variable       _N_
             contains the actual input observation number.

     DON'T:  Assume that setting the SAS automatic variable
             _ERROR_ will cause an input observation to be
             ignored or CA MICS processing to terminate.

     DON'T:  Use SAS language features not supported by the
             SAS release specified for use by the CA MICS
             update process.