now i am DOUBLE confused because this book seems to be 90% the same material as the part from Bridgman's Complete Guide to Drawing From Life .... except with the addition of Lock folds.

just checked on the internet archive. you are right, that's very confusing even more because the lock folds seems describes the same fold type as the half lock from dawing from life

yeah 😔 i think ill just stick to calling it half-lock, best not to make everyone as confused as i am

bridgeman complete guide is a condensed compilation of his life drawing other books, so probably has some language changes and maybe a few updates/ removal of information not needed, but is otherwise just 6 books in one.