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1 Format of Version 5 Babyl Files:
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2
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3 Warning:
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4
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5 This was written Tuesday, 12 April 1983 (by Eugene Ciccarelli),
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6 based on looking at a particular Babyl file and recalling various
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7 issues. Therefore it is not guaranteed to be complete, but it is a
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8 start, and I will try to point the reader to various Babyl functions
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9 that will serve to clarify certain format questions.
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10
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11 Also note that this file will not contain control-characters,
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12 but instead have two-character sequences starting with Uparrow.
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13 Unless otherwise stated, an Uparrow <character> is to be read as
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14 Control-<character>, e.g. ^L is a Control-L.
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15
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16 Versions:
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17
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18 First, note that each Babyl file contains in its BABYL OPTIONS
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19 section the version for the Babyl file format. In principle, the
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20 format can be changed in any way as long as we increment the format
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21 version number; then programs can support both old and new formats.
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22
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23 In practice, version 5 is the only format version used, and the
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24 previous versions have been obsolete for so long that Emacs does not
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25 support them.
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26
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27
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28 Overall Babyl File Structure:
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29
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30 A Babyl file consists of a BABYL OPTIONS section followed by
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31 0 or more message sections. The BABYL OPTIONS section starts
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32 with the line "BABYL OPTIONS:". Message sections start with
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33 Control-Underscore Control-L Newline. Each section ends
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34 with a Control-Underscore. (That is also the first character
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35 of the starter for the next section, if any.) Thus, a three
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36 message Babyl file looks like:
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37
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38 BABYL OPTIONS:
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39 ...the stuff within the Babyl Options section...
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40 ^_^L
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41 ...the stuff within the 1st message section...
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42 ^_^L
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43 ...the stuff within the 2nd message section...
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44 ^_^L
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45 ...the stuff within the last message section...
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46 ^_
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47
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48 Babyl is tolerant about some whitespace at the end of the
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49 file -- the file may end with the final ^_ or it may have some
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50 whitespace, e.g. a newline, after it.
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51
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52
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53 The BABYL OPTIONS Section:
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54
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55 Each Babyl option is specified on one line (thus restricting
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56 string values these options can currently have). Values are
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57 either numbers or strings. The format is name, colon, and the
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58 value, with whitespace after the colon ignored, e.g.:
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59
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60 Mail: ~/special-inbox
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61
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62 Unrecognized options are ignored.
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63
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64 Here are those options and the kind of values currently expected:
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65
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66 MAIL Filename, the input mail file for this
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67 Babyl file. You may also use several file names
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68 separated by commas.
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69 Version Number. This should always be 5.
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70 Labels String, list of labels, separated by commas.
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71
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72
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73 Message Sections:
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74
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75 A message section contains one message and information
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76 associated with it. The first line is the "status line", which
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77 contains a bit (0 or 1 character) saying whether the message has
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78 been reformed yet, and a list of the labels attached to this
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79 message. Certain labels, called basic labels, are built into
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80 Babyl in a fundamental way, and are separated in the status line
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81 for convenience of operation. For example, consider the status
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82 line:
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83
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84 1, answered,, zval, bug,
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85
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86 The 1 means this message has been reformed. This message is
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87 labeled "answered", "zval", and "bug". The first, "answered", is
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88 a basic label, and the other two are user labels. The basic
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89 labels come before the double-comma in the line. Each label is
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90 preceded by ", " and followed by ",". (The last basic label is
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91 in fact followed by ",,".) If this message had no labels at all,
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92 it would look like:
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93
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94 1,,
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95
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96 Or, if it had two basic labels, "answered" and "deleted", it
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97 would look like:
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98
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99 1, answered, deleted,, zval, bug,
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100
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101 The & Label Babyl Message knows which are the basic labels.
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102 Currently they are: deleted, unseen, recent, and answered.
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103
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104 After the status line comes the original header if any.
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105 Following that is the EOOH line, which contains exactly the
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106 characters "*** EOOH ***" (which stands for "end of original
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107 header"). Note that the original header, if a network format
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108 header, includes the trailing newline. And finally, following the
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109 EOOH line is the visible message, header and text. For example,
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110 here is a complete message section, starting with the message
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111 starter, and ending with the terminator:
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112
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113 ^_^L
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114 1,, wordab, eccmacs,
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115 Date: 11 May 1982 21:40-EDT
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116 From: Eugene C. Ciccarelli <ECC at MIT-AI>
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117 Subject: notes
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118 To: ECC at MIT-AI
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119
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120 *** EOOH ***
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121 Date: Tuesday, 11 May 1982 21:40-EDT
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122 From: Eugene C. Ciccarelli <ECC>
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123 To: ECC
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124 Re: notes
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125
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126 Remember to pickup check at cashier's office, and deposit it
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127 soon. Pay rent.
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128 ^_
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129
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130 ;;; Babyl File BNF:
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131
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132 ;;; Overall Babyl file structure:
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133
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134
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135 Babyl-File ::= Babyl-Options-Section (Message-Section)*
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136
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137
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138 ;;; Babyl Options section:
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139
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140
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141 Babyl-Options-Section
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142 ::= "BABYL OPTIONS:" newline (Babyl-Option)* Terminator
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143
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144 Babyl-Option ::= Option-Name ":" Horiz-Whitespace BOptValue newline
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145
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146 BOptValue ::= Number | 1-Line-String
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147
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148
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149
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150 ;;; Message section:
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151
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152
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153 Message-Section ::= Message-Starter Status-Line Orig-Header
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154 EOOH-Line Message Terminator
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155
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156 Message-Starter ::= "^L" newline
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157
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158 Status-Line ::= Bit-Char "," (Basic-Label)* "," (User-Label)* newline
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159
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160 Basic-Label ::= Space BLabel-Name ","
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161
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162 User-Label ::= Space ULabel-Name ","
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163
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164 EOOH-Line ::= "*** EOOH ***" newline
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165
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166 Message ::= Visible-Header Message-Text
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167
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168
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169 ;;; Utilities:
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170
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171 Terminator ::= "^_"
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172
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173 Horiz-Whitespace
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174 ::= (Space | Tab)*
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175
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176 Bit-Char ::= "0" | "1"
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