... "teaching grandmothers to suck eggs" The "code" of a rail is the height in "thou"- I prepared a table that was published in MRJ some time ago showing the code against the equivalent prototype lbs/yd figure- unfortunately I can't find the original of that, but I have a table showing the equivalent sizes in 4mm& 7mm for the various dimensions quoted in the BS spec. (just converted it to a word document as I find I can't attach an Excel spreadsheet! best wishes Richard Jones 1763_180527_180000000.png Attachment: attach_847_799_Rails.doc 400 posted: 18 Aug 2010 10:46 from: Martin Wynne Hi Richard, Many thanks for that. just converted it to a word document as I find I can't attach an Excel spreadsheet! It's better not to attach files in DOC, XLS, and similar Windows "business" formats as many members will not be able to access them (me included). PDF is a suitable alternative which most members will be able to read and print out if required. However, I've converted your table ...