[barcode] Deciphering command line options

[Alessandro Rubini]

> I'm trying to print a sheet of sticky labels which will be used to label tape 
> cartridges, but I just cannot fathom how the -t, -g and -m options interact.

> The label sheets we have are 15 rows x 3 cols for a total of 45 labels per 
> Label sheet = A4 size,
> Label cells = (w) 51mm x (h) 15mm
 
> Horizontal gap between cells across the row: 14mm
> Vertical gap between cells in a column: 3mm
> 
> The label "area" is pretty much centered on the page: 14mm margin left & 
> right; top/bottom margins are 15mm (although I've noticed some sheets are cut 
> a bit different, and have a 14~14.5mm top margin).
> 
> So we have horizontally:
> 14mm [51mm label] 14mm [51mm label] 14mm [51mm label] 14mm 

> Vertically:
> 15mm (top margin)
> [15mm label]
> 3mm
> ... repeat x14 rows...
> 15mm (bottom margin)
> 
> I hope this all makes sense.

Yes, thanks.
 
> I thought maybe rounding might be an issue, so recently I've converted all my 
> measurements to points using 1mm = 2.857142857 points

I don't think so. Postscript uses float numbers for erverything.
 
> The closest I've had to getting the result I want is using:
> 
> -e code39 -c -u 'mm' -p 210x297 -t 3x15+0+0-0-7 -g 45x12+17+10 -m 3,2

Ok.