DM: Data Model
The Chandra Data Model (DM) separates the structure of the data from the file format in which it is stored, which means that any program that uses the DM (e.g. the CIAO tools) is not format-specific; FITS and ASCII formats are supported.
All tools that use the Data Model have built-in filtering and binning on the command line, including the full regions syntax. For instance, an output source list from wavdetect can be filtered by dmcopy to create an event list excluding point sources. The Data Model stores the filtering applied to a file in the data subspace.
The Making Images & Filtering Data with the Data Model thread is a starting guide to how to use the Data Model. Also see the DM ahelp page and the DM manuals.