In English, abbreviations have traditionally been written with a full stop/period/point in place of the deleted part to show the ellipsis of letters – although the colon and apostrophe have also had this role – and with a space after full stops (e.g. "A. D."). In the case of most acronyms, each letter is an abbreviation of a separate word and, in theory, should get its own termination mark. Such punctuation is diminishing with the belief that the presence of all-capital letters is sufficient to indicate that the word is an abbreviation.