Known bugs/features

• The FAINT option will currently attempt to apply the faint-to-bright conversion to ALL the filenames listed. It SHOULD check the keywords and only attempt to convert genuine FAINT files.
• In general, Xselect has no cognizance of the particular manipulations required by the various instrument-mode combinations.
• The code implicitly assumes the event data, spectra etc are in the first extension, which is currently the default for FRFREAD files and XSPEC files. Future decisions to pack lots of extensions into a single FITS file are not yet supported!
• The select obscat command does not store a history of the selections whereby the current catalogue was reached. It only remembers the last selection expression applied.