angle mod → a modification of layout by shifting the left-hand bottom row to the left, for ISO Layout keyboards (used in Europe).
row stagger → the layout of the normal computer keyboard, where the columns are slanted in a semi-regular way.
sfb → same finger bigram. In keyboard letter layout design, sfb means using the same finger to type 2 letters. e.g. on qwerty, typing my, loll.
redirect → In keyboard letter layout design, it is a out-of-order roll. i.e. using same hand, same row, but order is neither left-to-right nor right-to-left. e.g. on qwerty, typing ads.