The main subroutine (figure 6) loops over all selected exposures and instruments (MOS1/MOS2) present in the input directory. It creates one (or two, if a CCD is operated in TIMING mode) event list for a single exposure, from all relevant ODF material and (if they exist) the good time intervals generated by tabgtigen and the list of bad pixels (from the CCF or produced internally). In a first step (figure 7) it loops over all CCD/nodes, calling in sequence:
Then evselect is called on the resulting event list(s) applying (by default) the destructive filter selection (#XMMEA_EM) && (FLAG & 0x762a0000) == 0. Note that in case of emchain, (#XMMEA_EM) is not applied: here events flagged as OUT_OF_FOV and REJECTED_BY_GATTI are kept in the list (as they are useful for background assessments and flare screening, respectively). For a description of the event attribute based selection, refer to the documentation of the SAS package evatt.
All the event list files created (one per CCD/node) are merged by evlistcomb, creating one event list per mode (IMAGING, TIMING). Finally evselect is called on the resulting events list(s), with (CCDNR == $node$ccd) && GTI(merged GTI file,TIME) for all CCD/nodes.
In the EPIC MOS imaging mode, the EVENTS binary table of the calibrated event list file contain 12 columns i.e TIME, RAWX, RAWY, DETX, DETY, X, Y, PHA, PI, FLAG, PATTERN and CCDNR. DETX and DETY are the event position in the focal plane array. X and Y are the event position in sky coordinates. PHA is the pulse analyser channel and PI the pulse independent channel. CCDNR is the CCD number. For a description of the FLAG column, see the documentation of the SAS package evatt. The PATTERN definition is given in the documentation of the task emevents (see also figure 12).
In the EPIC MOS timing mode, the EVENTS binary table of the calibrated event list file contains only 7 columns: the spatial coordinates RAWY, DETX, DETY, X, Y are not present as (in this mode) only one axis (RAWX) contains spatial information whereas the other axis is a measure of the arrival time of the event.