If DEFMTD is set to STD or COM, WIDTH1 is the width of a single echelle order. To find this value load the ORDREF on the display using LOAD/IMAGE and use for example the commands GET/CURSOR or EXTRACT/TRACE and PLOT/IMAGE TRACE. A superior method which will be needed later in the reduction any way is to extract a column and to produce a plot on the hardcopy device. Let x be a column somewhere in the middle of the frame. The following sequence of commands will do the job:
SET/PLOT BIN=ON
PLOT/COL ima @x
SEND/PLOT ps2usr0
The default method for DEFINE/ECHELLE is STD. However, it happens that the order definition procedure mixes order and inter-order: this is likely to occur in the blue where the order spacing becomes less than the width of each order. Set the parameter DEFMTD=COM