-1   Send messages in version 5 format. The Message Agent from version 5 cannot read messages sent by the Message Agent from version 6 and later. You should ensure that the compression option is set to -1 until all Message Agents in your system are upgraded to version 6 or later.

0   No compression.

1 to 9   Increasing degrees of compression. Creating messages with high compression can take longer than creating messages with low compression.