dmitry_vk implemented threading support for Windows port of Steel Bank Common Lisp. I decided to help by taking care of less complicated, but more platform-specific issues (I/O, timers, &c). Therefore I've started my own fork of Dmitry's source tree. He maintains a separate branch containing the threading support proper, to facilitate review and integration, and an experimental branch that is periodically merged with my branch in both directions.
Of course we want our code to be accepted upstream. Now, when everything seems to work, it's time to document our proposed changes. Dmitry has already done it for his "purified" branch.
Here is my attempt to document my own changes. I'm not going into minor details yet (github comments are be better for it than a separate text). What I want is giving the big picture, documenting purpose and reason of each modification, listing imminent and potential problems and unresolved issues.