(TIFF) A file format used for still-image bitmaps, stored in tagged fields. {Application programs} can use the tags to accept or ignore fields, depending on their capabilities. While TIFF was designed to be eXtensible, it lacked a core of useful functionality, so that most useful functions (e.g. lossless 24-bit colour) requires nonstandard, often redundant, eXtensions. The incompatibility of eXtensions has led some to eXpand "TIFF" as "Thousands of Incompatible File Formats". Compare GIF, PNG, JPEG. (1997-10-11)