You don't have to use LZW to construct an application/postscript file.
You do have to use LZW to construct a GIF file.
This has not been shown to be true. In fact there is every reason to
believe it isn't true.
LZW is a particular methodology for picking common substrings out of
an input stream. Once selected these strings are replaced with
references to their previous occurences. On reception the process is
undone using another specific method for building a dictinary of
It is quite possible that an alternative unpatented method exists for
picking strings that generates the same format.
Until a few minutes ago I was pretty sure that this wasn't the case,
but after thinking about LZW some more, I have to admit that this is a
(The "unpatented" compression algorithm might well be less efficient
in terms of compressed output than the patented version, but by adding
some lookahead to the string matching algorithm it might even generate
smaller compressed output than vanilla LZW...Compression would be much
slower, but for compress-once/decompress-many uses of GIF it might be
At any rate, I concur on the wait-and-see strategy.