Winzip Split Archive File
Winzip is a file archive program that is also able to compress files as well as many other functions, it also supports the creation of split volumes, when an archive is split the files use the file extension .z01, the number after the z corresponds to the split file number.
An example of this if the file was split in to 5 parts then they would be listed as z01 - z04 the main file from the archive uses the .zip extension which then uses the parts to decompress the archive.
How to open .z01 files?
Software to open .z01 files
What are .z01 files