GIF89a support multiple images, and even display methods for those
images nativly. The "transparent" information is a hack...
Transparancy in the GIF89a spec is defined as overlay information,
specifically onto the background image. True GIF files _always_
will have a background, not browser-defined... Belive it or
not it is actually possible to create 24 bit deep images using
the GIF specification, but that something that no display tool
will be able to support.
The GIF89a spec would allows you to do simple animation if you
ps. I would take TIFF as a native browser image file format, yesterday!
* Supports 1 .. 24 bit images nativly
Colormapped, non-colormapped, etc.
* Supports multiple compression methods, None, LZW, JPEG.
* Supports transparancy
* Every real image processing, manipulation tool can write it.
* Image could contain copyright information
(GIF can only contain this information as a comment)