The task rgssources can either modify a previously-created source list or create a new one, depending on the value of the parameter filemode. If filemode=`create', the name of the newly created file is read from parameter srclist. If on the other hand filemode=`modify', the name of the existing file to be edited must instead be supplied to srclist. Note that if filemode=`create' and srclist gives the name of an existing file, this existing file may (subject to the SAS_CLOBBER setting) be completely overwritten.
Although sources are never deleted from previous lists, some of the column entries may be altered. Older-format source tables are automatically converted to conform to the current format. (Note however that NO other extensions to the source list file are upgraded in format by rgssources.)
If filemode=`create', the name of the RGS instrument must be supplied via the parameter instexpid. If on the other hand filemode=`modify', the instrument designation is read from header of the old file.
Note that all sources must originally have come from one of the following three categories. Their labels (see description of column LABEL, section 5) will reflect that fact.