-  PCA will not call, or invoke, your user routine image if it is
       linked with warnings or errors.

    -  You must define a logical name to access the user routine
       image if it is not found in SYS$SHARE.

    -  A system service routine which is invoked from a user-
       supplied routine should be written in the C language (as
       referenced by the /USER_ROUTINE qualifier in the glossary
       of the DIGITAL Performance and Coverage Analyzer for OpenVMS
       Reference Manual). If written in some other languages, it may
       have the effect of locking up PCA. Examples are provided in
       PCA$EXAMPLES.