Very Computer

I'm writing a simple function to return the number of times a given GIF file
will loop through it's animations.  I know about the Netscape2.0 app.
extension, but what I want to know is this:  can this block ever be found
past the start of the image data?

Every GIF i've examined follows this sequence:

headers
[global color table]
[misc. app extensions -- including netscape's]
image data*
end

But does it *have* to?  Can the netscape block ever come after the start of
the image data?  Thanks in advance for any help.

Richard
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Richard Moss
Danrich Internet LLC
Makers of deal-mac
http://deal-mac.com/