Gaia region files are organised as a table of data, with additional information in the header which both specifies the source symbols and directs how their size and orientation should be calculated from the information in the table. Details of this arrangement can be found in reference [1]. Task slconv permits only circles as source symbols, but the type of symbol and its specification expression can easily be altered by editing the output region file after running slconv. To allow for greater flexibility however slconv allows the user to copy additional columns from the input FITS source list to the gaia region file. (Columns entitled `Id', `ra' and `dec' are always generated in the output.) These column names should be listed in the parameter extragaiacolumns. Note that the default setting of this parameter is to copy two columns from the source list, namely RADEC_ERR and RATE. If columns of these names are not present in the input source list, or not desired in the output, they should be explicitly removed from extragaiacolumns at the time of invocation of slconv.
