The study of paper stocks can be important in many branches of historical investigation that involves written drawn or printed paper materials. However in the 40 years since allan stevenson demonstrated that watermarks are twins relatively few scholars have shown an inclination to use this type of technique much less develop them further. As well as twinship other important principles of paper study include: 1) distinguishing the two sides of the sheet; 2) defining the position of the wiremark on the mould; 3) identifying the more-or-less standard of paper. Another significant concept when studying paper stocks is to infer from paper archives, the character of the white paper as it came into the relevent office or shop (where it was used). This is what is meant by the archival principles of paper study. 22 references notes.