Block Type - 4 MARKER BLOCK.

This is a special block that specifies a marker (MARKER) in the
voice data.

During the voice output, this MARKER can be passed to the application
program for syncronization control.

The voice driver module (CT-VOICE.DRV) provided to application developers
will store the MARKER into the status word during voice output.

The MARKER Must be within the range from 1 0FFFFEH.

The BLKLEN is fixed a 2.

        ┌──────┬──────┬────────┬─────┬──────┬─────┐
        │  04  │      │ BLKLEN │     │   MARKER   │
        └──────┴──────┴────────┴─────┴──────┴─────┛