Lol, mnh is mint never hung, so it is completely unblemished. some people hang them in their albums with hinges-which is fine if they are used, but not so nice if they are mint. this brings the value down. any other ? just ask. mark
as to my comment above, ALL the stamps have original gum on the back. they are all nice and shiny just as received from the UNPA. Now the souvenir sheet is also mnh and has original gum but the gum is a dull gum you cant see,not shiny like the stamps, but it IS THERE! I know because unfortunately I have had a few stick together on me. Oh well, such is life.
Stampers should recognize that when someone claims a stamp to be: "Mint - Never Hinged"; it means that the stamp is in the same condition it was when released by the printer/engraver. That means the stamp is in a "completely unchanged" state of printing and gluing from when it was first issued. Re-gluing obviously does not meet that requirement. Licking the stamp, adding glue (gum), removing glue or disturbing the glue, adhering a hinge to mount it to an album page - or changing the gum (glue) in any way - removes the stamp from that "BEST" condition. If there are additional flaws, like torn-off, short & pulled perforations, or folds & creases,etc., which happened while separating the stamp from the sheet or in storage, or any loss of glue due to age, scuffing of the surfaces, etc., -- these must be described also because condition and grade are a "standard" against which pricing is determined. Values in a catalog are for a particular grade and condition -- not the generic stamp. Most modern "unused" stamps are priced in catalogs for a state of "Never Hinged".