I found this in some magazine
Their are four different compressor modes built into the compressor module. The first two are manual modes: Manual Peak and Manual RMS. Manual Peak responds to transients which cross the threshold and can be used in a similar fashion to a brickwall limiter when set with a high ratio and fast attack and release settings. Manual RMS responds to the average level and is more useful as a moderate channel compressor. The Manual RMS is the default compressor on each channel.
The remaining two modes have automatic attack and release characteristics. The Auto Slow Opto behaves like an optical compressor, with slow attack and release characteristics and was a favourite of ours on live vocals, enabling us to get a consistent vocal sound from our system. The final mode is the Auto Punchbag which has a faster, VCA-like, auto response – a good starting point with drums for users not overly familiar with attack and release settings who want to avoid the two manual modes.
I note that our dealer left us on auto punchbag which seems wrong for our environment in a church.
Google found a pointer to an AH article that was 404.
Supposedly written by the AH compressor designer and explained all 4 of them in detail.
Suggestions:
1 - Repost the article so it actually shows up not 404
2 - Insert links in the documentation to all these articles that elaborate on the terse text that is provided in the manual.