Gee, it seems pretty obvious to me:

- IBM intends to distribute as .zip
- IBM uses the 7-Zip utility to make the intended .zip
- Someone at IBM by mistake clicked 7z instead of zip as the desired 
compression method in the 7-zip utility



-----Original Message-----
From: IBM Mainframe Discussion List [mailto:IBM-MAIN@LISTSERV.UA.EDU] On Behalf 
Of Tony Harminc
Sent: Monday, September 19, 2016 3:19 PM
Subject: Re: k4t4949b (September 2016 refresh of the z/OS 2.2 manuals)

On 19 September 2016 at 14:31, Kevin Minerley <> wrote:
> Unfortunately, this is working as designed.  If indeed it's the 
> sk4t-4949-xx deliverable, it is large.  As a matter of fact, were it to be be 
> put on a dual-layer DVD it wouldn't fit (at least in this pass).

The file as I just downloaded it is about 1GB (1,118,616.064 bytes according to 
Windows). This would fit comfortably on even a single-layer DVD. It isn't even 
all that much bigger than a CD. Maybe IBM has smaller DVDs than most of us...

But in any case I have a good deal of trouble seeing why this is relevant.

> Most modern zip utilities work against it.  Personally, I use 7-zip 
> but when manufactured it's the same zip utilities we have been using since 
> the days of physical media.

Really? I think of Winzip as *the* standard commercial Windows-based zip 
utility, and it doesn't accept it. Neither does the Windows built-in zip 
handling in Windows explorer. Neither does the java command. And the reason is 
clear: it's not a zip file. The first two bytes of the file are X'377ABCAF' or 
ASCII "7z..". The zip file specification
requires that a zip file start with a header of X'504B0304' or ASCII "PK..", no 
matter what the compression method within the file.

So opening this file pretty much requires that 7-zip or some other compatible 
decompressor be installed. If that's really what IBM intends, then the file 
should not be marked as .zip .

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