Proprietary Zip Compression
I recently received a Zip file which could not be opened with WinZip or WinRar. This wasn’t entirely unexpected since I knew that WinZip and PKWARE developed their own high end Zip compression algorithms. When you use the maximum compression feature in these programs, your files will be compressed using a proprietary technology which will require the original application to decompress it. For instance, you if use the maximum compression on a file using WinZip, you woulnd’t be able to uncompress it using Pkzip.
If you receive Zip files, you’ll need to have both applications to handle the most common archives. WinZip is a commercial application which will require you to purchase it to legally use. The cost is only $29.95 USD so it’s not unreasonable. Fortunately, PKWARE released Zip Reader which is a free utility to uncompress their archives.