% @(#)preparback.hlq	17.1.1.1 (ESO-IPG) 01/25/02 17:50:38 
%++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
%.COPYRIGHT  (c)  1991 European Southern Observatory
%.IDENT      preparback.hlq
%.AUTHOR     Pascal Ballester, IPG/ESO
%.KEYWORDS   MIDAS, help files, PREPARE/BACKGROUND
%.PURPOSE    On-line help file for the command: PREPARE/BACKGROUND
%.VERSION    1.0  29-JUL-1991 : Creation, PB
%----------------------------------------------------------------
\se
SECTION./BACK
\es\co
PREPARE/BACKGROUND					10-AUG-1994 PB
\oc\su
PREPARE/BACKGROUND   [step] [init] [back_tab] [order_tab] [descr]
	low-level command; create table back.tbl
\us\pu
Purpose:    
            Low level command called by BACKGR/ECHELLE. Prepare table
            of background reference positions from order fitting coefficients
            stored in table [order_tab] and descriptor [descr].
\up\sy
Syntax:     
            PREPARE/BACKGROUND [step] [init] [bkgtab] [ordtab] [descr]
\ys\pa
            step      = step along X axis between background reference 
                        positions.
\ap\pa
            init      = initialization flag to enforce the creation
                        of a new table (init = INI). Default is NULL:
                        a new table will be created only if the step
                        or scan parameters have been modified, or if the
                        background table does not exist.
\ap\pa
            bkgtab    = name of output background table. Default is
                        back.tbl.
\ap\pa
            ordtab    = name of input order table. Default is order.tbl.
\ap\pa
            descr     = generic name of descriptors conataining coefficients
                        of orders fitting. Default is COEFF.
\ap\exs
Examples:
\ex
            PREP/BACK   5  INI 
\xe\sxe