A file name of up to 80 characters can be specified. The parameters for each entry in the source catalog are below. Lower case letters in this list are optional. This is useful, for example, for finding phase calibrators near target sources. All of these coordinates are listed in the .sum file.
Various stations require different epoch coordinates.
For example, the VLBA only understands J2000 coordinates while some other sites only understand B1950. This is the date at which the coordinates of the reference sources were determined. For purposes of pointing antennas, the value of this date that is used is not very important. But if you are trying to phase reference, phase the VLA at a high frequency, or derive positions for correlation, this is an issue that should be dealt with properly. This is the name of the source.