# Modified elements

- IFCENTER, FRQOFF1, and FRQOFF2 columns from the FrontEnd table are reversed for each row where IFFLIPS is true. This factorizes the sign issues when dealing with IF2 instead ot IF1,
- The column BAND is read under the name PART for IMB-FITS version lower than 2. Same for REC1 and REC2 read under the names RECEIVER and BAND respectively,
- REFCHAN is patched to correct values (instead of 1) when dealing with continuum backend (1 channel per chunk),
- all the BackEnd columns, namely PART, REFCHAN, CHANS, DROPPED, USED, PIXEL, RECEIVER, BAND, POLAR, REFFREQ, SPACING, and LINENAME are sliced into memory to more values than from the file in order to factorize at once the MSET CALIBRATION BANDWIDTH tuning. NAXIS2 is updated accordingly. See section for details,
- the columns MJD, INTEGTIM and ISWITCH are compressed if MSET CALIBRATION BAD is NO (this is the default). In this case all rows where ISWITCH is 0 are removed. Two new columns FOREPOIN and BACKPOIN are added as cross pointers between the original and compressed columns. See section for details.
- the DATE-OBS and DATE-END stamps of each subscan are patched if MSET CALIBRATION MJDINTER is YES. See HELP for details.