All AT&T UNIX PC paper documentation and on-screen usage documentation uses the term "Volume Home Block", but never "Volume Header Block". So in all images and documentation below, please replace in your head as you read, any instances of "Volume Header Block" with "Volume Home Block"
The MightyFrame seems to like (or at least read) the VHB on a hard drive formatted by the UNIX PC. On startup with a UNIX PC-formatted drive connected, the MightyFrame reads:
"executing loader from drive 0"