0

Turns the safety mechanism off. Explicit synchronization and errorchecking are not performed. This level is appropriate for productionruns of code that have already been thoroughly tested. 

2

Detects potential race conditions in multithreaded S3L operations on parallel arrays. To avoid race conditions, an S3L function locks all parallel array handles in its argument list before proceeding. This safety level causes warning messages to be generated if more than one S3L function attempts to use the same parallel array at the same time. 

5

In addition to checking for and reporting level 2 errors, performsexplicit synchronization before and after each call and locates eacherror with respect to the synchronization points. This safety level isappropriate during program development or during runs for which a small performance penalty can be tolerated. 

9

Checks for and reports all level 2 and level 5 errors, as well as errorsgenerated by any lower levels of code called from within S3L. Performs explicit synchronization in these lower levels of code and locates each error with respect to the synchronization points. This level is appropriate for detailed debugging following the occurrenceof a problem.