Library /sys$common/syshlp/pca$help.hlb HELP, Parameters  *Conan The Librarian (sorry for the slow response - running on an old VAX)

 topic

    Specifies the name of the command or topic with which you need
    help.

 subtopic

    Specifies a particular qualifier or parameter on which you want
    further information, or a keyword that gives you information
    about a range of qualifiers or parameters.