At one point there were two separate products that were combined to create DOS/BATCH. It was sold until the late 70's but deemphasized in favor of RT-11. I have a bunch of DECtapes of this material queued up to be read in the next few months. The one document that I'm missing was the companion to the DOS/BATCH handbook that was the sys admin guide which describes the system generation process. A copy of a DOS/BATCH distribution tape that John Wilson and I read has been forwarded to Bob Supnik. Hopefully there's still someone left who would be willing to give permission for its release similar to that given for the version of RT that he has.