Comet search parameters are defined here. These are valid for Comet version 2013.01.x.
Parameters for all versions of Comet can be found here.
Entries marked with an * are new parameters.
Entries marked with an ** are redefined compared to previous release.
To generate a comet.params file appropriate for your Comet binary, issue the command "comet -p". Here is an example comet.params file. Here's a link to all parameter descriptions on a single web page.