Memo:   How to merge databases in dbedit
Author: L. Petrov
Date:   2003.09.29

   Dbedit allows to read several databases or fringe output files and merge
them into one output databases. However, case should be taken during this
operation if more than one database is being read. First, Dbedit reads input 
databases into the scratch file of record of fixed length. Therefore, all
lcodes in input database should have the same dimension, except STRNAMES and
SITNAMES, because Dbedit never read these lcodes. Second, does not merge lists
of objects in two databases, f.e. list of cable calibration status. It means 
that most likely only lcodes generated by Fourfit or AIPS can be merged.
If the database has other lcodes, supplied by Calc, Dbedit, Solve then merging 
will most probably fail, since these lcodes may have different dimensions
and related to the lists in different order.

   There is a workaround in this situation. A user can strip database from 
lcodes which cannot be merged and leave only lcodes supplied by Fourfit or 
AIPS. First, it is necessary to learn the lcodes lists in both databases.
It can be done by running program dbhd3. It outs in the output file the list
of lcode names. Then a user should decide which lcodes Dbedit should read. 
These lcode names are put in the input file of wanted lcodes: one lcode name
per line. The name of this file is supplied as a value of the qualifier
Input_lcode in the $Input_Filter section of the control file for Dbedit.