When MRTCAL opens an index file (usually index.mrt), it builds what is called the input index in memory. However, for many reasons the contents of the index file may be disordered. In order to give friendly lists to the user, the input index is implicitly sorted by observing date, then scan number, then backend identifier1. For example, the following files are ordered like this:
MRTCAL> $ls *.fits iram30m-4mhz-20100930s200-imb.fits iram30m-fts-20100930s201-imb.fits iram30m-4mhz-20100930s201-imb.fits iram30m-wilma-20100930s200-imb.fits iram30m-fts-20100930s200-imb.fits iram30m-wilma-20100930s201-imb.fits MRTCAL> mlist in ! "in" lists the input index N.V ProjId Source Date UT Scn Backe ObsType Swi Calibr 1.1 054-09 CONTROLD 30-SEP-2010 20:52:47.0 200 4MHZ CALIBRATE PSW NONE 2.1 054-09 CONTROLD 30-SEP-2010 20:52:47.0 200 WILMA CALIBRATE PSW NONE 3.1 054-09 CONTROLD 30-SEP-2010 20:52:47.0 200 FTS CALIBRATE PSW NONE 4.1 054-09 CONTROLD 30-SEP-2010 20:53:37.0 201 4MHZ TRACKED PSW NONE 5.1 054-09 CONTROLD 30-SEP-2010 20:53:37.0 201 WILMA TRACKED PSW NONE 6.1 054-09 CONTROLD 30-SEP-2010 20:53:37.0 201 FTS TRACKED PSW NONE
From the input index, the user has to build the current index2 with MFIND. They can be identical (MFIND called without argument), or the current index can be a subset of the input index. For example:
MRTCAL> mfind /backend 4mhz I-FIND, 2 entries in Current indeX MRTCAL> mlist ! No argument: list the current index N.V ProjId Source Date UT Scn Backe ObsType Swi Calibr 1.1 054-09 CONTROLD 30-SEP-2010 20:52:47.0 200 4MHZ CALIBRATE PSW NONE 4.1 054-09 CONTROLD 30-SEP-2010 20:53:37.0 201 4MHZ TRACKED PSW NONE
The number which can be seen in the first column is used by
several commands to identify the file to be processed (for example,
CALIBRATE 1). In most of the cases, especially when dealing with
a data set which does not evolve, using this number in procedures is
acceptable. However, there are some use cases where one needs to pay
attention: