Parameter to be sepcified are:
The input files are mantained using the DIRA package for astronomical catalogs.
The format for the input date and time is yy/mm/dd hh:mm:ss. It is converted internally to years and fraction of years, with the convention that years 80-99 represent 1980-1999, and 00-79 represent 2000-2079. Four digits per year are also acceptable. It is important to note that the epoch in the output file will be represented as years from 1900, if two digits are used, or absolute years, if four digits are used. Obviously, consistence for the date representation in the input catalog is essential.
This format is useful for plotting the time coverage of a set of sources, plotting the first field (source ID) versus the second (epoch of observations).
The representative observation for each source is chosen as the first in time (date of observation) in the ordered data set of the observations. It is possible that it is not the best choice, e.g. its position or name can be quite atypical. The output catalog is sorted for decreasing number of observations.