How to use NSOpenPanel to select a file with ext "zip.001"

Question

I use NSopenPanel to select a file with common ext, for example:

openDlg.allowedFileTypes = [NSArray arrayWithObjects: @"zip", nil];

But how to select a file named as "test.zip.001"?

allowedFileTypes set to @"001" and @"zip.001" neither works.