Lets you choose a file to be compressed. You may compress any file except MacCompress files and files ending in ".z" or ".Z"; these are assumed to already be compressed.
If the input file is named "MyFile", then the output file will be named "MyFile.Z". If the file name is too long to add ".Z", you will get an error message. File names are limited to 31 characters by the Mac file system, so your file name must be 29 characters or less if you want to compress it in Unix format.
The percent compression shown is for the data fork only -- the resource fork is copied. Thus if your original file has a data fork of 100 bytes, then 40% compression means the data fork of the output file 40 bytes shorter, or 60 bytes.
