When an external catalogue is given, if a source listed in the source list is not included in the external catalogue, then the source is ignored in processing. The same information can be obtained from the column INCATFLG in the input source-list, that is, if the value in INCATFLG is false, the source is not processed.
On the other hand, if an external catalogue is not given, and if the input source-list is given but does not contain the column INCATFLG, then all the sources specified (a single source or all) are processed.
