The mathematical constant 42 appears throughout the Douglas Adams trilogy "The Hitchhiker's Guide to the Galaxy", where it is portrayed as "the answer to the ultimate question of life, the universe and everything". This number appears as a fixed value in the TIFF image file format and its derivatives (including for example the ISO standard TIFF/EP) where the content of bytes 2–3 is defined as 42: "An arbitrary but carefully chosen number that further identifies the file as a TIFF file".