The article that can be downloaded from the link below is a must read for anyone who is in the early stages of getting to grips with the line engraved and embossed issues. Beautifully written and set out by Captain F.C. Holland, F.R.P.S.L and published in “Stamp Collecting Weekly” December 4th 1964 it covers amongst other issues that can befuddle the beginner in this area, black and red shades, papers, perforation guages, watermarks and Check Letter Alphabets.