The IBM PC layout, particularly the Model M, has been extremely influential, and today most keyboards use some variant of it. This has caused problems for applications developed with alternative layouts, which require keys that are in awkward positions on the Model M layout – often requiring the pinkie to operate – and thus require remapping for comfortable use. One notable example is the escape key, used by the vi editor: on the ADM-3A terminal this was located where the Tab key is on the IBM PC, but on the IBM PC the Escape key is in the corner; this is typically solved by remapping Caps Lock to Escape. Another example is the Emacs editor, which makes extensive use of modifier keys, and uses the Control key more than the meta key (IBM PC instead has the Alt key) – these date to the Knight keyboard, which had the Control key on the "inside" of the Meta key, opposite to the Model M, where it is on the "outside" of the Alt key; and to the space-cadet keyboard, where the four bucky bit keys (Control, Meta, Super, Hyper) are in a row, allowing easy chording to press several, unlike on the Model M layout. This results in the "Emacs pinky" problem.