Quote from Mike:

    > Rather, you simply split the file into 218 parts ending with the
    > character "5" and then stripped that final character from each part.  Thus the
    > "decompressor" is nothing more than a reassembler,
    > concatenating the parts and reappending
    > the character "5" after each.

Well, that's exactly the definition of lossless compression. Look at e.g. how js crunch works: you create a dictionary of common sequences, split the file on those sequences recursively and then reassemble it by joining in reverse. Gzip, bzip2, &c, &c, it's all the same thing. Split the file by a common sequence and reassemble it by that. Patrick just created a customized compressor that went only 1 level deep.

Normally you'd need a delimiter to separate those chunks, a delimiter that doesn't occur in the chunks e.g. through padding or escaping. That, in turn, increases the filesize, and now you're in trouble. What Patrick did was to use EOF as a new fresh "delimiter" that doesn't occur anywhere, and at a cost of zero bytes, no less.

Cheating, or inventive.