The SCA Callable Interface allows you to use SCA within
    independent application programs. This allows you to integrate SCA
    into alternative user-interfaces and lets you generate specialized
    reports based on SCA information.

    The SCA Callable Interface contains two components. The first is a
    set of routines termed Callable Command Routines, which comprise
    a high-level interface which must always be used, regardless of
    the type of application. This provides a very simple callable
    interface to SCA, which will be sufficient for most applications.

    Callable Command Interface Routines

    o  SCA$ASYNCH_TERMINATE

    o  SCA$CLEANUP

    o  SCA$DO_COMMAND

    o  SCA$GET_INPUT

    o  SCA$INITIALIZE

    o  SCA$LOCK_LIBRARY

    o  SCA$PUT_OUTPUT

    o  SCA$UNLOCK_LIBRARY

    The second component is a set of routines termed Callable
    Query Routines. The Callable Query Routines comprise a lower-
    level interface to the FIND command. Using this interface, an
    application has control over the specification of queries and the
    manipulation of query results.

    Callable Query Initialization/Cleanup Routines

    o  SCA$QUERY_CLEANUP

    o  SCA$QUERY_INITIALIZE

    Callable Query Question Building Routines

    o  SCA$QUERY_PARSE

    o  SCA$QUERY_SELECT_OCCURRENCE

    o  SCA$SELECT_OCCURRENCE

    Callable Query Result Manipulation Routines

    o  SCA$GET_ATTRIBUTE

    o  SCA$GET_ATTRI_KIND_T

    o  SCA$GET_ATTRI_VALUE_T

    o  SCA$GET_OCCURRENCE

    o  SCA$QUERY_GET_ATTRIBUTE

    o  SCA$QUERY_GET_ATTRI_KIND_T

    o  SCA$QUERY_GET_ATTRI_VALUE_T

    o  SCA$QUERY_GET_OCCURRENCE

    Callable Query Miscellaneous Routines

    o  SCA$GET_CURRENT_QUERY

    o  SCA$QUERY_COPY

    o  SCA$QUERY_FIND

    o  SCA$QUERY_GET_NAME

    Message Handling

    The SCA callable interface handles all messages the same way:
    it signals them. If you want control over the display of such
    messages, you must establish a condition handler. Establishing a
    condition handler is optional.

    Rules for Calling SCA Routines

    o  Most SCA routines are not AST-reentrant; therefore, you should
       not call an SCA routine (except SCA$ASYNCH_TERMINATE) from an
       AST routine that may currently be interrupting an SCA routine.

    o  Your program must not disable ASTs.

    o  If your program uses event flags, you must use the VMS RTL
       routines (LIB$RESERVE_EF, LIB$GET_EF, and LIB$FREE_EF) in order
       to coordinate the use of event flags between your program and
       SCA.

    o  Except for SCA$ASYNCH_TERMINATE, do not call SCA from within an
       SCA callback routine or from within a routine that is handling
       a condition signaled by SCA.

    o  Your program must not unwind when handling a condition signaled
       by SCA.