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1.1 ! root 1: >From [email protected] (Robert Krawitz) Mon Nov 30 10:56:46 1987 ! 2: ! 3: Let's see if I remember my BNF for babyl files; this corresponds to ! 4: version 5: ! 5: ! 6: ! 7: File := <header> ! 8: <message>* ; Some say there must be at least one message. ! 9: ! 10: Header := Babyl Options:\n ! 11: <header-option>* ! 12: |^_ ! 13: ! 14: Header-option := <header-token> ; See note [5] ! 15: : * ! 16: <value> ! 17: ! 18: header-token := [^\000-\017:\177-\377]* ; Not these characters [tab is OK] ! 19: header-value := ditto, if a list, each element separated by a comma and ! 20: a space. ! 21: ! 22: message := \^L\n ! 23: [01], ; See note [1] below ! 24: ( <attribute>,)* ; Note space before and comma after token ! 25: , ! 26: ( <label>,)* ; ditto, see note [4] below ! 27: \n ! 28: <header>* ; See note [1] and [2] below ! 29: *** EOOH ***\n ! 30: <header>* ; See note [2] below ! 31: \n ! 32: <body> ! 33: \^_ ! 34: ! 35: attribute := unseen | ! 36: last | ; Not all programs implement this. It ! 37: ; generally only gets used internally, and ! 38: ; isn't written out to a file. ! 39: >last | ; Babyl uses this for a deleted message at the ! 40: ; end. It shouldn't be written out to a file. ! 41: deleted | ! 42: recent | ; Not all programs implement this. It refers ! 43: ; to a message in the last batch of new mail; ! 44: ; thus it probably shouldn't be written out to ! 45: ; a file during a normal save although it ! 46: ; makes sense to write it out in an emergency save. ! 47: filed | ! 48: answered | ! 49: forwarded | ! 50: redistributed | ! 51: badheader | ; Not all programs implement this ! 52: filed ; Not all programs implement this ! 53: ! 54: label := [^\000-\020,\177-\377]* ; No control chars, ! 55: ; whitespace, commas, rubout, or high bit set ! 56: ! 57: header := [^\000-\020:\177-\377]*: ! 58: <header-line> ! 59: <header-line>* ! 60: ! 61: header-line := [ \t][^\n]*\n ; Continuation lines must be indented ! 62: ! 63: body := (.*\n)* ; See note [3] below ! 64: ! 65: ! 66: [1] A zero means that the headers have not been cleaned up, ! 67: reprocessed, toggled, or whatever. In this case there should be no ! 68: headers before the EOOH line. A one means that the headers have been ! 69: reprocessed. In this case, the original headers will typically be ! 70: before the EOOH line and the reformatted or whatever subset of headers ! 71: that the user should see will be after it. Note that in this case ! 72: it's permissible to garbage collect all headers before the EOOH line. ! 73: No one's defined what it means to garbage collect SOME of the headers ! 74: before this line, or what that means. ! 75: ! 76: [2] It's apparently permissible to add headers of the program's own ! 77: choosing before the EOOH line. Or at least, Rmail does so (it caches ! 78: a summary line) and nothing seems to object. There's no particular ! 79: guarantee that something else won't step all over it, though. Headers ! 80: after the EOOH line can be reformatted as the program wishes (e. g. ! 81: indent the header lines to the same distance, canonicalize machine ! 82: names) for display to the user. It's generally best for programs that ! 83: read a babyl file to look at the headers before the EOOH line if they ! 84: exist, since these should be untouched by the user. Remember, the ! 85: user can edit anything after the EOOH line. ! 86: ! 87: [3] A \^_ at the beginning of a line should be quoted somehow. The ! 88: normal way seems to be to decompose it into 2 characters: a ^ and a _. ! 89: Strictly speaking, it doesn't always have to be, since the following ! 90: text would have to be parsable as a message, but some programs don't ! 91: try to use that much intelligence. Oh well. ! 92: ! 93: [4] Labels, or keywords as they are often called, are generally ! 94: defined by the user, although it's not entirely impermissible for a ! 95: program to use these for its own purpose (e. g. a keyword named ! 96: RemindMe might be used to automatically find important messages). ! 97: Some people also want these used to cache other state implemented by ! 98: certain programs; this use is undefined. Note that all keywords used ! 99: should be inserted in a header-option named Keywords:. Can a keyword ! 100: have the same name as an attribute? Who knows? It's probably not a ! 101: good idea, since some programs use the concept of <labels> = ! 102: <keywords> + <attributes>. Sigh. ! 103: ! 104: [5] Some tokens are standardized in meaning. Common tokens are Mail ! 105: inboxes, babyl file version number, which is currently 5, labels used ! 106: in messages, window format for Zmail, anything else you want to be ! 107: associated with a file. Be warned that labels should be a complete ! 108: list of all user-defined keywords used in the file, so if you add a ! 109: new label to a message, you should add it to this list. You should ! 110: also have a Babyl version: 5 file attribute (look in a babyl file for ! 111: details). ! 112: ! 113: Anyone know if there actually is a "formal" standard? This was done ! 114: quickly from memory and a Zmail manual, but there are at least three ! 115: programs around that use Babyl files (zmail, babyl, and emacs/rmail) ! 116: and someone at SIPB was going to write a command-based mail reader ! 117: similar to Unix Mail but operating on babyl files, and someone (of ! 118: course not me :-)) should probably write xbabyl :-) ! 119: ! 120: References: ! 121: ! 122: ITS/Tops-20 INFO file on babyl (who wrote it? ECC? GZ?) ! 123: ! 124: Zmail manual (the MIT version was written by RMS; ECC wrote the ! 125: section on Babyl file format) ! 126: -- ! 127:
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