Looping Is Not in the GIF Spec

The GIF89a specification defines the signature, the color tables, the LZW encoder, the four interlacing passes, transparency, and the per-frame delay. It does not define animation looping. Download it and search: the word "loop" does not appear in the document once. Every GIF you have ever watched repeat did so because of a 19-byte block that Netscape made up in 1995 and nobody ever standardized.…