command_context
    type:       $SCA_COMMAND_CONTEXT
    access:     read/write
    mechanism:  by reference

    An SCA command context.

 query_name
    type:       character string
    access:     read only
    mechanism:  by descriptor

    The name of the query in the context of the command context.

 occurrence
    type:       $SCA_HANDLE
    access:     read/write
    mechanism:  by reference

    An SCA occurrence handle that describes an occurrence.