The extract command can be used to generate spectra and lightcurves from an input event file. The default is to use the region file generated by the box and circle commands. A new region file name is input using /region=file. Output spectra(/phafile=) and lightcurves(/qdpfile=) are in ASCII format. The former is the old style XSPEC RDPHA output and you must use MKPHA to turn make a file that can be read by XSPEC. The light curve is a QDP file that can be read into xronos. It is in general better to use XSELECT to make lightcurves and spectra. The extract command is most useful for generating color-color diagrams for all the sources detected in an image generated from an events file, or for making an energy dependent PSF for a source, again if the events file is present.