MVS/XA
From Wikipedia, the free encyclopedia.

MVS/XA stands for MVS/Extended Architecture. This was a version of z/OS, which supported 31-bit addressing. It was vailable only on the high-end 43xx, and 308x and later ranges, and was replaced by MVS/ESA, then OS/390 and later z/OS.

The original article can be found at: http://en.wikipedia.org/wiki/MVS/XA.
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