NAME
        CMD_READ - Query the narrator device for mouth shape or other
                   synchronization events.


   SYNOPSIS
        Standard device command.


   FUNCTION
        Currently, there are three events which the user can inquire
        about from the narrator device.  These are: mouth shape changes,
        start of word, and start of syllable.  Each read request returns
        information about any or all of these events as determined by
        the bits set in the sync field of the read iorequest block.  in
        the case of mouth shape changes, each shape returned is guaranteed
        to be different from the previously returned shape to allow
        updating to be done only when necessary.  Each read request is
        associated with a write request by information contained in the
        iorequest block used to open the device.  since the first field
        in the read iorequest block is a write iorequest structure, this
        association is easily made by copying the write iorequest block
        (after the opendevice call) into the voice field of the read
        iorequest block.  if there is no write in progress or in the
        device input queue with the same pseudo unit number as the read
        request, the read will be returned to the user with an error.  This
        is also how the user knows that the write request has finished and
        that s/he should not issue any more reads.  Note that in this case
        the mouth shapes may not be different from previously returned values.


   INPUTS
        mouth_rb iorequest block with the voice field (a narrator_rb
        structure) copied from the associated write request with the
        following fields modified:

           io_Message - Pointer to message port for read request
           io_Command - CMD_READ
           io_Error   - Clear before issuing first read
           width      - 0
           height     - 0


   RESULTS
        As long as the speech is in progress, each read returns the
        following information in the mouth_rb iorequest block.

        If mouth shape changes are requested the following fields are
        modified:
           width  - Contains mouth width value in arbitrary units
           height - Contains mouth height value in arbitrary units
           shape  - Compressed form of mouth shapes (internal use only)


        ******  NEW FOR V37 NARRATOR

        If word synchronization is requested:
           sync   - Bit NDB_WORDSYNC is set

        If syllable synchronization is requested:
           sync   - Bit NDB_SYLSYNC is set

        Note that any or all of the above fields can be set and it is
        the user's responsibility to check for all possibilities.


   SEE ALSO
        cmd_write
        Exec input/output documentation.