📄 babyl
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>From rlk@think.COM (Robert Krawitz) Mon Nov 30 10:56:46 1987Let's see if I remember my BNF for babyl files; this corresponds toversion 5:File := <header> <message>* ; Some say there must be at least one message.Header := Babyl Options:\n <header-option>* |^_Header-option := <header-token> ; See note [5] : * <value>header-token := [^\000-\017:\177-\377]* ; Not these characters [tab is OK]header-value := ditto, if a list, each element separated by a comma and a space.message := \^L\n [01], ; See note [1] below ( <attribute>,)* ; Note space before and comma after token , ( <label>,)* ; ditto, see note [4] below \n <header>* ; See note [1] and [2] below *** EOOH ***\n <header>* ; See note [2] below \n <body> \^_attribute := unseen | last | ; Not all programs implement this. It ; generally only gets used internally, and ; isn't written out to a file. >last | ; Babyl uses this for a deleted message at the ; end. It shouldn't be written out to a file. deleted | recent | ; Not all programs implement this. It refers ; to a message in the last batch of new mail; ; thus it probably shouldn't be written out to ; a file during a normal save although it ; makes sense to write it out in an emergency save. filed | answered | forwarded | redistributed | badheader | ; Not all programs implement this filed ; Not all programs implement thislabel := [^\000-\020,\177-\377]* ; No control chars, ; whitespace, commas, rubout, or high bit setheader := [^\000-\020:\177-\377]*: <header-line> <header-line>*header-line := [ \t][^\n]*\n ; Continuation lines must be indentedbody := (.*\n)* ; See note [3] below[1] A zero means that the headers have not been cleaned up,reprocessed, toggled, or whatever. In this case there should be noheaders before the EOOH line. A one means that the headers have beenreprocessed. In this case, the original headers will typically bebefore the EOOH line and the reformatted or whatever subset of headersthat the user should see will be after it. Note that in this caseit's permissible to garbage collect all headers before the EOOH line.No one's defined what it means to garbage collect SOME of the headersbefore this line, or what that means.[2] It's apparently permissible to add headers of the program's ownchoosing before the EOOH line. Or at least, Rmail does so (it cachesa summary line) and nothing seems to object. There's no particularguarantee that something else won't step all over it, though. Headersafter the EOOH line can be reformatted as the program wishes (e. g.indent the header lines to the same distance, canonicalize machinenames) for display to the user. It's generally best for programs thatread a babyl file to look at the headers before the EOOH line if theyexist, since these should be untouched by the user. Remember, theuser can edit anything after the EOOH line.[3] A \^_ at the beginning of a line should be quoted somehow. Thenormal way seems to be to decompose it into 2 characters: a ^ and a _.Strictly speaking, it doesn't always have to be, since the followingtext would have to be parsable as a message, but some programs don'ttry to use that much intelligence. Oh well.[4] Labels, or keywords as they are often called, are generallydefined by the user, although it's not entirely impermissible for aprogram to use these for its own purpose (e. g. a keyword namedRemindMe might be used to automatically find important messages).Some people also want these used to cache other state implemented bycertain programs; this use is undefined. Note that all keywords usedshould be inserted in a header-option named Keywords:. Can a keywordhave the same name as an attribute? Who knows? It's probably not agood idea, since some programs use the concept of <labels> =<keywords> + <attributes>. Sigh.[5] Some tokens are standardized in meaning. Common tokens are Mailinboxes, babyl file version number, which is currently 5, labels usedin messages, window format for Zmail, anything else you want to beassociated with a file. Be warned that labels should be a completelist of all user-defined keywords used in the file, so if you add anew label to a message, you should add it to this list. You shouldalso have a Babyl version: 5 file attribute (look in a babyl file fordetails).Anyone know if there actually is a "formal" standard? This was donequickly from memory and a Zmail manual, but there are at least threeprograms around that use Babyl files (zmail, babyl, and emacs/rmail)and someone at SIPB was going to write a command-based mail readersimilar to Unix Mail but operating on babyl files, and someone (ofcourse not me :-)) should probably write xbabyl :-)References:ITS/Tops-20 INFO file on babyl (who wrote it? ECC? GZ?)Zmail manual (the MIT version was written by RMS; ECC wrote thesection on Babyl file format)-- ⌨️ 快捷键说明
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