ORIGINAL GUM.--Practically all stamps were, before issue, gummed on the back, and the actual gum so applied is known as "original": the usual abbreviation is "o.g.": it is also implied in the expression "MINT", which see. OVERPRINT.--An inscription or device printed upon a stamp additional to its original design. _Cf._ SURCHARGE. PAIR.--Two stamps joined together as when originally printed. Without qualification, a PAIR is generally accepted as being of two stamps side by side: if a pair of two stamps joined top to bottom is intended, it is spoken of as a _vertical_ pair. [Illustration: EXAMPLES OF SOME PHILATELIC TERMS. A "Bisect," or "Bisected Provisional." The One Penny stamp of Jamaica was in 1861 permitted to be cut in halves diagonally, and each half used as a halfpenny stamp.] PANE.--Entire sheets of stamps are frequently divided into sections by means of one or more spaces running horizontally or (and) vertically between similarly sized groups of stamps: each of these sections or groups is termed a PANE. PAPER.--The two main divisions of PAPER are HAND-MADE and MACHINE-MADE: the former is manufactured, as its name indicates, by hand, sheet by sheet, by means of a special apparatus; the latter is made entirely by the aid of machinery and generally in long continuous rolls, which are afterwards cut up as required. Each of these, apart from its substance, which may vary from the thinnest of tissue papers to almost thin card, is divisible according to its texture, distinguishable on being held up to the light, into-- WOVE, of perfectly plain even texture, such as is generally used for books. LAID: this shows lines close together, usually with other lines, an inch or so apart, crossing them--"cream laid" notepaper is an example. BÂTONNÉ is wove paper, with very distinct lines as wide apart as those on ordinary ruled paper. LAID BÂTONNÉ: similar to BÂTONNÉ, but the spaces between the distinct lines are filled in with laid lines close together. QUADRILLÉ paper is marked with small squares or oblongs. REP is the term applied to WOVE paper which has been passed between ridged rollers, so that it becomes, to use a somewhat exaggerated description, corrugated: the small elevation or ridge on one side of the paper coincides with a depression or furrow on the other side--the thickness of the paper is the same throughout. RIBBED paper, on the other hand, is different from REP, in that one side is smooth and the other is in alternate furrows and ridges--the paper is thinner in the furrows than it is on the ridges.