FUNCTION extensio,files
;
; This function returns a STRING array giving the extensions (i.e.,
; the part after the '.') in the STRING array of file names passed
; in 'files'.
;
out=files
FOR i=0,N_ELEMENTS(files)-1 DO BEGIN
    dotpos=STRPOS(files(i),'.')
    IF dotpos(0) NE -1 $
        THEN out(i)=STRMID(files(i),dotpos(0)+1,STRLEN(files(i))-dotpos-1) $
        ELSE out(i)='-1'	; missing file name ?!?
    ; The next two lines won't work under DOS as presently coded.
    gzpos=STRPOS(out(i),'.gz')
    IF (gzpos(0) NE -1) THEN out(i)=STRMID(out(i),0,gzpos(0))
ENDFOR
RETURN,out
END