Mixed (Perforations).—In some of the 1901-7 stamps of New Zealand, the original perforation was to some extent defective: such portions of the sheet were patched with strips of paper on the back and re-perforated, usually in a different gauge.
Mounted.—Usually applied to indicate that a stamp, which has been trimmed close to the design, has had new margins added. And see Fake.
Native-made paper.—See Paper.
Obliteration.—A general term used for any mark employed to cancel a stamp and so render it incapable of further use.
Obsolete.—Strictly, an obsolete stamp is one which has been withdrawn from circulation and is no longer available for postal use; but the term is often applied simply to old issues, no longer on sale at the post-office.
Original die.—The first engraved piece of metal, from which the printing plates are directly or indirectly produced.
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.