dick@tjalk.UUCP (Dick Grune) (05/15/86)
Thank you all for your remarks, criticisms and general interest in our proposal for recommended key bindings for emacses. We have tried to incorporate them and still (or "therefore") get a consistent body, which we present herewith. The general set-up has remained the same, but many details have been changed, and much of the rationale has been touched up. Dick Grune dick@vu44.UUCP Sjoerd Mullender sjoerd@vu44.UUCP ---------------------------------------------------------------- 1. INTRODUCTION At this moment we, the authors, have at our disposal 7 emacses, all slightly or more than slightly different in their key bindings, enough to confuse novice and expert alike. Emacs's great strength, its programmability, turns into a weakness and chaos rages. In an attempt to bring some order into this chaos we have drawn up the complete lists of initial key bindings of each emacs (i.e. the bindings the unsuspecting user gets when he just calls the specific emacs) and printed them side by side, on a virtual piece of paper, 210 columns wide. Upon examination, patterns began to emerge, and we have observed the following. 1. Almost all elementary functions, functions "that every emacs should have," are always bound to the same keys, ^H and ^Z being the only problems. These key bindings are brought together in Class A in the proposal. 2. Most of the non-essential functions have a "home", a binding about which a majority of the emacses agree. Those for which a home could be identified are grouped in Class B. 3. All emacses agree that ^X- or ESC- followed by a capital letter is either bound to nothing or to the same function as ^X- or ESC- followed by the corresponding small letter. 4. None of the emacses directly solves the problems caused by the fact that on some systems ^S and ^Q are preempted by the terminal communication, as X-OFF and X-ON. Any emacs should supply reasonable alternatives. This has led us to submit the attached proposal, which is accompanied by a rationale. The version presented here is version 2, into which we have incorporated reactions to version 1; these reactions have helped to clear up many details. We welcome further comments and suggestions, which will serve for version 3, to be issued perhaps a year from now. In the meantime we shall endeavour to give the present proposal as wide a dissemination as possible. We thank all those who have given us their support. Dick Grune dick@vu44.UUCP Sjoerd Mullender sjoerd@vu44.UUCP Vrije Universiteit de Boelelaan 1081 1081 HV Amsterdam the Netherlands 2. PROPOSAL Proposal for recommended key bindings in emacs-like editors. Version 2. May 1986. SCOPE The recommendations in this proposal apply to the key bindings as they appear initially --upon calling the editor-- to the user who has given no customization or initialization information. This proposal is NOT to be construed as a recommendation against differing local or personal key bindings, and is intended solely to reduce confusion in the unsuspecting user and as matter for consideration to future emacs authors. It concerns itself primarily with the use as a document text editor rather than a program text editor. The editor functions are grouped into 3 classes, according to their relative importance: Class A: functions the user can expect to be present. Class B: optional functions, which the user can nevertheless expect to be present in a wordprocessor/development environment. Class C: specialized optional features, which are common enough for a recommendation to be in order. In addition to these classes, two general recommendations are given. Class A: Character commands: ^B go backward character ^D delete next character ^F go forward character ^T transpose characters ^? delete previous character Line commands: ^A go to beginning of line ^E go to end of line ^K delete to end of line Intra-line commands: ^N go to next line ^P go to previous line Word commands: ESC-b go backward word ESC-d delete next word ESC-f go forward word ESC-^? delete previous word Window commands: ^V page this window ^Z scroll forward ^X-1 delete other windows ^X-2 split window ^X-d delete window ^X-o go to other window ESC-^V page other window ESC-< go to beginning of file ESC-> go to end of file ESC-v page backward ESC-z scroll backward Buffer commands: ^X-^B list buffers ^X-b switch to named buffer ^X-k delete named buffer File commands: ^X-^F find named file ^X-^I insert named file ^X-^M save modified files ^X-^R read named file ^X-^S save file ^X-^W write named file Region commands: ^@ set mark ESC-SPACE set mark ^W delete region to internal buffer ^Y insert from internal buffer ^X-^X exchange cursor and mark White space commands: ^I insert tab ^J insert newline and indent ^M insert newline ^O insert newline and backup Search commands: ^R search reverse ^S search forward ESC-q query replace string ESC-r replace string Miscellaneous commands: ^C exit ^X-^C exit ^G abort (directly mapped) ^L redraw screen ^Q quote next character ^U argument prefix ^^ replacement for ^Q (directly mapped) ^\ replacement for ^S (directly mapped) ^] alternate prefix Class B: Word commands: ESC-t transpose words Sentence commands: ^X-^? delete to beginning of sentence ESC-a go backward sentence ESC-e go forward sentence ESC-k delete to end of sentence Paragraph commands: ESC-[ go backward paragraph ESC-] go forward paragraph ESC-j justify paragraph Window commands: ^X-^ enlarge window Region commands: ESC-w copy region to internal buffer ESC-^W delete region to end of internal buffer Case commands: ESC-c capitalize word ESC-l lower case word ESC-u upper case word White space commands: ^X-^O delete blank lines ESC-\ delete horizontal space Macro commands: ^X-( start keyboard macro ^X-) stop keyboard macro ^X-e execute keyboard macro Information commands: ^X-= display cursor position ESC-? help System commands: ^X-^E compile ^X-^N display next error ^X-! give command to command interpreter ^_ call command interpreter Class C: Line commands: ^X-^T transpose lines ESC-m go to first non-blank Window commands: ^X-n go to next window ^X-p go to previous window ESC-, go to beginning of window ESC-. go to end of window Buffer commands: ESC-~ set buffer not modified Case commands: ^X-^L lower case region ^X-^U upper case region Internal editor commands: ESC-ESC evaluate internal expression ESC-x execute internal command ^X-* display version number Abbreviations: ^X-^A add local abbreviation ^X-^H inverse add local abbreviation ^X-+ add global abbreviation ^X-- inverse add global abbreviation Layout control: ^X-. set indent column ^X-; set comment column ^X-f set fill column ESC-; indent to comment column Scroll sideways: ^X-< scroll left ^X-> scroll right Parentheses: ESC-^B go backward parenthesis ESC-^F go forward parenthesis CAPITAL LETTERS IN A PREFIXED COMMAND Key strokes consisting of a prefix (^X- or ESC-) followed by a capital letter should be bound to the same command as the prefix followed by the corresponding small letter. DIRECT MAPPING OF ^S, ^Q AND ^G All key bindings that include a ^S or ^Q should have a corresponding binding with ^\ substituted for ^S and ^^ for ^Q; all key bindings that include ^G should result in abort. If the editor supports direct mapping (low-level interpretation), this should be used, so that new bindings will automatically inherit the substitution. If not, appropriate explicit bindings should be supplied. END OF PROPOSAL 3. RATIONALE 3.1 The concept The reason for this proposal at all is the same as that for any standard: some design decisions are to a large extend arbitrary, and to reduce the ensuing complexity, additional artificial order has to be imposed. We feel that the subject has at present reached a certain maturity and has not yet petrified. For an editor to be used efficiently, the user must be able to operate it by reflexes only. Having to learn a slightly different set of reflexes leads to much aggravation, more so than having to learn, e.g., a variant of a programming language. 3.2 The approach We have considered the initial key bindings of emacs2.10 (Unipress/Gosling), jove (Jonathan Payne/Unison World), PerfectWriter (Perfect Software), MicroEmacs (Curt Jutzi, jutz@pogo), GNU (Richard M. Stallman), scame (Leif Samuelsson, leif@erisun), MicroEMACS (Dave Conroy, conroy@dec-rex). For Class A and B we only considered those key bindings that were defined in at least four of the above. The key bindings for which no rationale is given below were either unanimous or defined by some and not contradicted by any of the others. We have not concerned ourselves with small semantic differences: "next-paragraph" will go to the beginning of the next paragraph on some editors and to the end of this paragraph on others; "transpose-characters" may transpose cursor[-2..-1] or cursor[-1..0], etc. These are considered equivalent, since the user has direct optical feedback. 3.3 Specific key bindings ^H is left unbound. It is usually bound to go-backward-character or to delete-previous-character, without clear preference for either. Both of these are available under other keys (^B and ^?). Users working on low-grade telephone lines may need to avoid ^? since it is often generated by noise; they may bind delete-previous-character to ^H and unbind ^?. ^Z Some systems have the possibility to suspend a running process; this action is traditionally coupled to the ^Z key. It is, however, not at all universal and requires considerable OS support. We feel therefore that we can still use ^Z (and its companion ESC-z) for scrolling --with suspending, calling the command interpreter, etc., bound to ^_ . ^] Most editors do not use a third prefix besides ^X and ESC; among those that do, there is no consensus, with ^H, ^Z, ^\, ^^ and ^X-4 being used. ^] is not used by any editor for anything. ESC-SPACE Not all terminals or OSs can transmit a NUL character (^@). ESC-SPACE can serve to bind set-mark to. Since no more single characters are available, a direct mapping cannot be found, nor is one needed, in the absence of compound key sequences with ^@. ^X-^F, ^X-^R Generally there exist two commands, "read file into new buffer" and "read file into existing buffer", called "find named file" and "read named file" respectively here. They are bound to various permutations of ^X-^F, ^X-^R and ^X-^V, the latter being called "visit file", but being identical to "find named file". The proposed assignment seems more mnemonic and seems to have a slight majority. 3.4 Capital letters in a prefixed command The beginning user would have difficulty in telling apart ^X-^S, ^X-s, ^X-S, ESC-^S, ESC-s and ESC-S, with assorted meanings like save-file, forward-search, call-spelling-checker, center-line or scratch-buffer. Some tutorials print ^X-S when they mean ^X-s. Some users may want to use their terminals with CAPS LOCK on. Some terminals with function keys send ESC-@ to ESC-O for them; if, however, function keys are to play a role, local customization will be necessary anyway, which is outside the scope of this proposal. 3.5 ^S and ^Q ^S and ^Q are used by some communication protocols and will then cause a great deal of confusion, both to the user and to the computer. It seems preferable to lift this problem out of the user realm and into the editor. The mapping ^S -> ^\ ^Q -> ^^ is preferable to ^S -> ^^ ^Q -> ^\ since ^^ is difficult to produce on some terminals and ^Q is the rarer of the two. It is the binding in much of the material that comes with GNU, Unipress and jove. 3.6 Fancy search facilities Many emacses provide two levels of search facilities, one searching for a simple string match, and a fancier one, e.g., incremental search or search for a regular expression. We do not provide recommendations for the latter, since we feel that those who use them will want to choose their own key bindings (like binding them in the place of the simple ones). Some editors govern the choice with a mode variable. END OF RATIONALE