For quite some time now, various source versions had already been available by leaks. An 8080 Altair version (4K?), an early generic 6502 8K version, a CP/M 5.x version, and an 8086 version. And the labels from the 6502 version apply very well to a disassembly of early 6800 8K versions for Altair 680 and SWTPC, though the 5-byte float support needs to be reconstructed.
Admittedly they were all a bit lacking in that they only hint at the original PDP-10 macro-fied version, which this release seems to be. And this still doesn't fulfill my quest for a clean 68000 version with binary math routines aside from the horribly segmented Mac OS version that's full of all sorts of new-age post-5.x stuff. (There's a 5.x decimal-math version for Tandy 6000 Xenix, but I never found a binary-math Xenix version.) But I'll be happy to look at what this version brings to the whole collection of MS-BASIC source code.
This all has meaning to me because I started on a TRS-80, and I was always disassembling its BASIC, followed by looks inside 6809 and 68000 versions. It's been fun trying to trace the ancestry of all the various bits of it. I sometimes say that I learned assembly language from Bill Gates because I learned so much from the code for BASIC. And I've actually been using this knowledge lately with a project to build a computer around a 68HC11 CPU. It's very convenient to be able to re-assemble it as necessary.