Diagnosing and Avoiding Errors

Understanding How the SAS Supervisor Checks a Job

To better understand the errors that you make so that you can avoid others, it is important to understand how the SAS Supervisor checks a job. The SAS Supervisor is the part of SAS that is responsible for executing SAS programs. To check the syntax of a SAS program, the SAS Supervisor does the following:

reads the SAS statements and data
translates the program statements into executable machine code or intermediate code
creates data sets
calls SAS procedures, as requested
prints error messages
ends the job

The SAS Supervisor knows

the forms and types of statements that can be present in a DATA step
the types of statements and the options that can be present in a PROC step

To process a program, the SAS Supervisor scans all the SAS statements and breaks each statement into words. Each word is processed separately; when all the words in a step are processed, the step is executed. If the SAS Supervisor detects an error, then it flags the error at its location and prints an explanation. The SAS Supervisor assumes that anything it does not recognize is an error.

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