A weight map (WMAP) is a 2-D image that has been binned in detector coordinates (i.e. the DET column in a Chandra event list). This image can either be stored in the WMAP block of a spectrum created by dmextract:

unix% dmextract "sources.evt2[bin pi]" sources.pi wmap="[bin det=8]"

or as an image by using the DM binning syntax with dmcopy:

unix% dmcopy "sources.evt2[energy=500:2000][bin det=8]" sources.wmap8

The WMAP is used as input to the mkwarf and mkacisrmf tools. Refer to the help files for those tools for more information on how it is used.