SET QUALITY

        LAS\SET QUALITY q

    FIND will select only observations of quality better than Q  (i.e.  less
    than  Q). When originally written, unless the real time acquisition sys-
    tem detected a severe problem, all observations have quality 0, a priori
    the  best.  The  quality flag of an observation can be changed using the
    TAG command. See HELP TAG for the recommended quality scale.