The first of multiple files that make up a split archive created with WinZip; uses the same compression as a standard .ZIP file, but must be decompressed along with the related split archives (.Z02, .Z03, etc.).
Split archives are often used to shrink the size of large files for e-mail attachments or file downloads. They can only be decompressed if all the split archive segments are available.
To decompress a series of z01, z02… files you need to do the following
1) Change all .z01, .z02 extensions to .001, .002 and so on.
2) The last extension in compressed series will have a .zip extension. If you have 8 segments, change .zip to .008.
3) Join all segments using “MacHacha”
4) Change the extension of the file produced by MacHacha?to .zip
5) Use “The Unarchiver” to decompress the .zip file produced by MacHacha.
References:
http://www.fileinfo.com/extension/z01