Here is a proposed encoding for "Font X". It is not invertible, and it doesn't have to be. We never send Font X, we only display it upon receipt of DEC Special Graphics and DEC Technical characters, or when we have selected "Display Controls". The DEC Technical Character set leaves nine positions undefined. On a real DEC VT320, these nine characters all display themselves as reverse question marks, which is already a legitimate DEC Technical character. So this creates nine undefined positions in Font X. Because DEC Technical and DEC Special Graphics have certain characters in common, or even repeated within a single set, we have certain single Font X characters representing two or more DEC characters, leaving still more Font X positions undefined. Remember, the object of this exercise is to make Font X as compatible with Apple's Symbol encoding as possible, so if users change the font of Font X material to Symbol, as much of it as possible will make sense. I am enclosing two tables. The first is sorted in DEC encoding order. The second is the same table, sorted in Font X encoding order. There are 297 entries in each table because of the duplicate mappings, but Font X itself contains exactly 256 positions, of which 23 are undefined (and should therefore display as boxes on the Mac screen). The undefined characters are listed, and the duplicate characters are listed as many times as they appear. The columns in the tables are: MAC: The first column shows the Font-X encoding in decimal. DEC: The second column shows the DEC encoding of the character in decimal. For the DEC Technical Set, the encodings are 8-bit: 160-254. SET: The third column tells which character-SET this character belongs to: DC0 = Display Controls for C0. SGA = DEC Special Graphics, ASCII part (i.e. 02/00 through 05/14). SGS = DEC Special Graphics, Special part (i.e. 05/15 through 07/14). DC1 = Display Controls for C1. TEC = DEC Technical. FONT-X-NAME: Describes the Font-X character. For Display Controls, the two characters that should be displayed in a single character cell are given, followed in parentheses by the actual ASCII (or ISO) name of the character, for example "Display Ctrl SH (SOH)" means that ASCII 001 (SOH) is displayed as "SH" in a single character cell, like this: ____ |S | | H| ---- SYMBOL-NAME: Describes the Apple Symbol character that has the same encoding as the Font X character. This shows what happens if users display Font X text in the Apple Symbol font. Each name is preceded by a digit: 0 Means an exact match 1 Means not an exact match, but pretty close, glyphically speaking 2 Means it's a totally different character I have tried to maximize the number of 0's and minimize the 2's. For DEC Special Graphics I got: 54 0's 13 1's 28 2's and for DEC Technical I got: 64 0's 11 1's 21 2's Overall I got: 118 0's 24 1's 137 2's (including the 64+ "Display Control" characters) Most of the 2's are because DEC Special graphics contains the first 4 columns of ASCII, but ASCII is pretty much absent from Symbol. Display controls, of course, are all 2's, because none of them are in the Symbol font. Here is the first table, in DEC encoding order (256 entries): MAC DEC SET FONT-X-NAME SYMBOL-NAME Here is the second table, in Font-X encoding order (297 entries because of all the duplications -- but remember, the duplicate entries are still only one character in the set. The set contains 256 character positions, of which 41 are undefined. MAC DEC SET FONT-X-NAME SYMBOL-NAME 000 000 DC0 Display Ctrl NU (NUL) 2 UNDEFINED 001 001 DC0 Display Ctrl SH (SOH) 2 UNDEFINED 002 002 DC0 Display Ctrl SX (STX) 2 UNDEFINED 003 003 DC0 Display Ctrl EX (ETX) 2 UNDEFINED 004 004 DC0 Display Ctrl ET (EOT) 2 UNDEFINED 005 005 DC0 Display Ctrl EQ (ENQ) 2 UNDEFINED 006 006 DC0 Display Ctrl AK (ACK) 2 UNDEFINED 007 007 DC0 Display Ctrl BL (BEL) 2 UNDEFINED 008 008 DC0 Display Ctrl BS (BS) 2 UNDEFINED 009 009 DC0 Display Ctrl HT (HT) 2 UNDEFINED 009 098 SGS Display Ctrl HT (HT) 2 UNDEFINED 010 010 DC0 Display Ctrl LF (LF) 2 UNDEFINED 010 101 SGS Display Ctrl LF (LF) 2 UNDEFINED 011 011 DC0 Display Ctrl VT (VT) 2 UNDEFINED 011 105 SGS Display Ctrl VT (VT) 2 UNDEFINED 012 012 DC0 Display Ctrl FF (FF) 2 UNDEFINED 012 099 SGS Display Ctrl FF (FF) 2 UNDEFINED 013 013 DC0 Display Ctrl CR (CR) 2 UNDEFINED 013 100 SGS Display Ctrl CR (CR) 2 UNDEFINED 014 014 DC0 Display Ctrl SO (SO) 2 UNDEFINED 015 015 DC0 Display Ctrl SI (SI) 2 UNDEFINED 016 016 DC0 Display Ctrl DL (DLE) 2 UNDEFINED 017 017 DC0 Display Ctrl D1 (DC1) 2 UNDEFINED 018 018 DC0 Display Ctrl D2 (DC2) 2 UNDEFINED 019 019 DC0 Display Ctrl D3 (DC3) 2 UNDEFINED 020 020 DC0 Display Ctrl D4 (DC4) 2 UNDEFINED 021 021 DC0 Display Ctrl NK (NAK) 2 UNDEFINED 022 022 DC0 Display Ctrl SY (SYN) 2 UNDEFINED 023 023 DC0 Display Ctrl EB (ETB) 2 UNDEFINED 024 024 DC0 Display Ctrl CN (CAN) 2 UNDEFINED 025 025 DC0 Display Ctrl EM (EM) 2 UNDEFINED 026 026 DC0 Display Ctrl SU (SUB) 2 UNDEFINED 027 027 DC0 Display Ctrl EC (ESC) 2 UNDEFINED 028 028 DC0 Display Ctrl FS (FS) 2 UNDEFINED 029 029 DC0 Display Ctrl GS (GS) 2 UNDEFINED 030 030 DC0 Display Ctrl RS (RS) 2 UNDEFINED 031 031 DC0 Display Ctrl US (US) 2 UNDEFINED 032 032 SGA Space 0 Space 032 095 SGA Space 0 Space 033 033 SGA Exclamation mark 0 Exclamation mark 034 125 SGS Pound Sterling Sign 2 For Every (upside down A) 035 035 SGA Number sign 0 Number sign 036 036 SGA Dollar sign 2 There Exists (backwards E) 037 037 SGA Percent sign 0 Percent sign 038 038 SGA Ampersand 0 Ampersand 039 112 SGS Horizontal Line - Scan 3 2 Such that 040 040 SGA Left Parenthesis 0 Left Parenthesis 041 041 SGA Right Parenthesis 0 Right Parenthesis 042 042 SGA Asterisk 1 Centered asterisk 043 043 SGA Plus Sign 0 Plus sign 044 044 SGA Comma 0 Comma 045 045 SGA Hyphen, Minus Sign 0 Minus sign 046 046 SGA Period, Full Stop 0 Period 047 047 SGA Solidus, Slash 0 Solidus, slash 048 048 SGA Digit Zero 0 Digit Zero 049 049 SGA Digit One 0 Digit One 050 050 SGA Digit Two 0 Digit Two 051 051 SGA Digit Three 0 Digit Three 052 052 SGA Digit Four 0 Digit Four 053 053 SGA Digit Five 0 Digit Five 054 054 SGA Digit Six 0 Digit Six 055 055 SGA Digit Seven 0 Digit Seven 056 056 SGA Digit Eight 0 Digit Eight 057 057 SGA Digit Nine 0 Digit Nine 058 058 SGA Colon 0 Colon 059 059 SGA Semicolon 0 Semicolon 060 060 SGA Left angle bracket 0 Left angle bracket 061 061 SGA Equals sign 0 Equals sign 062 062 SGA Right angle bracket 0 Right angle bracket 063 063 SGA Question mark 0 Question mark 064 064 SGA Commercial At sign 2 Identical to 065 065 SGA Capital Letter A 0 Capital Greek Alpha 066 066 SGA Capital Letter B 0 Capital Greek Beta 067 067 SGA Capital Letter C 2 Capital Greek Chi 068 068 SGA Capital Letter D 2 Capital Greek Delta 069 069 SGA Capital Letter E 0 Capital Greek Epsilon 070 070 SGA Capital Letter F 2 Capital Greek Fi 071 071 SGA Capital Letter G 2 Capital Greek Gamma 072 072 SGA Capital Letter H 0 Capital Greek Eta 073 073 SGA Capital Letter I 0 Capital Greek Iota 074 074 SGA Capital Letter J 2 Alternate lowercase theta 075 075 SGA Capital Letter K 0 Capital Greek Kappa 076 076 SGA Capital Letter L 2 Capital Greek Lambda 077 077 SGA Capital Letter M 0 Capital Greek Mu 078 078 SGA Capital Letter N 0 Capital Greek Nu 079 079 SGA Capital Letter O 0 Capital Greek Omicron 080 080 SGA Capital Letter P 2 Capital Greek Pi 081 081 SGA Capital Letter Q 2 Capital Greek Theta 082 082 SGA Capital Letter R 2 Capital Greek Rho 083 083 SGA Capital Letter S 2 Capital Greek Sigma 084 084 SGA Capital Letter T 0 Capital Greek Tau 085 085 SGA Capital Letter U 2 Capital Greek Upsilon 086 086 SGA Capital Letter V 2 Alternate lowercase sigma 087 087 SGA Capital Letter W 2 Capital Greek Omega 088 088 SGA Capital Letter X 2 Capital Greek Xi 089 089 SGA Capital Letter Y 2 Capital Greek Psi 090 090 SGA Capital Letter Z 0 Capital Greek Zeta 091 091 SGA Left Square Bracket 0 Left square bracket 092 192 TEC Therefore sign 0 Therefore sign 093 093 SGA Right Square Bracket 0 Right square bracket 094 118 SGS Box-Drawing T Bottom 1 Perpendicular (inverted T) 095 115 SGS Horizontal Line - Scan 9 1 Underscore 096 111 SGS Horizontal Line - Scan 1 1 Extension for radical 097 225 TEC Lowercase Greek alpha 0 Lowercase Greek alpha 098 226 TEC Lowercase Greek beta 0 Lowercase Greek beta 099 227 TEC Lowercase Greek chi 0 Lowercase Greek chi 100 228 TEC Lowercase Greek delta 0 Lowercase Greek delta 101 229 TEC Lowercase Greek epsilon 0 Lowercase Greek epsilon 102 230 TEC Lowercase Greek fi 0 Lowercase Greek fi 103 231 TEC Lowercase Greek gamma 0 Lowercase Greek gamma 104 232 TEC Lowercase Greek eta 0 Lowercase Greek eta 105 233 TEC Lowercase Greek iota 0 Lowercase Greek iota 106 119 SGS Box-Drawing T Top 2 Alternate greek theta 107 235 TEC Lowercase Greek kappa 0 Lowercase Greek kappa 108 236 TEC Lowercase Greek lambda 0 Lowercase Greek lambda 109 110 SGS Vert/Horiz Cross Centered 2 Lowercase Greek mu 110 238 TEC Lowercase Greek nu 0 Lowercase Greek nu 111 215 TEC Capital Greek Omega 2 Lowercase Greek omicron 112 123 SGS Lowercase Greek pi 0 Lowercase Greek pi 112 240 TEC Lowercase Greek pi 0 Lowercase Greek pi 113 234 TEC Lowercase Greek theta 0 Lowercase Greek theta 114 242 TEC Lowercase Greek rho 0 Lowercase Greek rho 115 243 TEC Lowercase Greek sigma 0 Lowercase Greek sigma 116 244 TEC Lowercase Greek tau 0 Lowercase Greek tau 117 249 TEC Lowercase Greek upsilon 0 Lowercase Greek upsilon 118 196 TEC Capital Greek Delta 2 Alternate lowercase omega 119 247 TEC Lowercase Greek omega 0 Lowercase Greek omega 120 248 TEC Lowercase Greek xi 0 Lowercase Greek xi 121 241 TEC Lowercase Greek psi 0 Lowercase Greek psi 122 250 TEC Lowercase Greek zeta 0 Lowercase Greek zeta 123 117 SGS Box-Drawing T Right 1 Left brace 124 198 TEC Capital Greek Fi 2 Vertical bar 125 116 SGS Box-Drawing T Left 1 Right brace 126 200 TEC Similar to, Centered tilde 0 Similar to, Centered tilde 127 127 DC0 Display Ctrl DT (DEL) 2 UNDEFINED 128 128 DC1 Display Ctrl 80 2 UNDEFINED 129 129 DC1 Display Ctrl 81 2 UNDEFINED 130 130 DC1 Display Ctrl 82 2 UNDEFINED 131 131 DC1 Display Ctrl 83 2 UNDEFINED 132 132 DC1 Display Ctrl 84 (IND) 2 UNDEFINED 133 133 DC1 Display Ctrl 85 (NEL) 2 UNDEFINED 134 134 DC1 Display Ctrl 86 2 UNDEFINED 135 135 DC1 Display Ctrl 87 2 UNDEFINED 136 136 DC1 Display Ctrl 88 (HTS) 2 UNDEFINED 137 137 DC1 Display Ctrl 89 2 UNDEFINED 138 138 DC1 Display Ctrl 8A 2 UNDEFINED 139 139 DC1 Display Ctrl 8B 2 UNDEFINED 140 140 DC1 Display Ctrl 8C 2 UNDEFINED 141 141 DC1 Display Ctrl 8D (RI) 2 UNDEFINED 142 142 DC1 Display Ctrl 8E (SS2) 2 UNDEFINED 143 143 DC1 Display Ctrl 8F (SS3) 2 UNDEFINED 144 144 DC1 Display Ctrl 90 (DCS) 2 UNDEFINED 145 145 DC1 Display Ctrl 91 2 UNDEFINED 146 146 DC1 Display Ctrl 92 2 UNDEFINED 147 147 DC1 Display Ctrl 93 2 UNDEFINED 148 148 DC1 Display Ctrl 94 2 UNDEFINED 149 149 DC1 Display Ctrl 95 2 UNDEFINED 150 150 DC1 Display Ctrl 96 2 UNDEFINED 151 151 DC1 Display Ctrl 97 2 UNDEFINED 152 152 DC1 Display Ctrl 98 2 UNDEFINED 153 153 DC1 Display Ctrl 99 2 UNDEFINED 154 154 DC1 Display Ctrl 9A 2 UNDEFINED 155 155 DC1 Display Ctrl 9B (CSI) 2 UNDEFINED 156 156 DC1 Display Ctrl 9C (ST) 2 UNDEFINED 157 157 DC1 Display Ctrl 9D (OSC) 2 UNDEFINED 158 158 DC1 Display Ctrl 9E (PM) 2 UNDEFINED 159 159 DC1 Display Ctrl 9F (APC) 2 UNDEFINED 160 160 TEC UNDEFINED 2 Double down arrow 161 217 TEC Capital Greek Upsilon 0 Capital Greek Upsilon 162 039 SGA Apostrophe 0 Foot/Minute/Prime 163 121 SGS Less-Equal 0 Less-Equal 163 188 TEC Less-Equal 0 Less-Equal 164 179 TEC Upper L to lower R diagonal 1 Fraction slash 165 194 TEC Infinity 0 Infinity 166 246 TEC Function-of sign, Script f 0 Script f 167 180 TEC Upper R to lower L diagonal 2 Club suit 168 096 SGS Diamond (solid) 0 Diamond (solid) 169 182 TEC Inverted Not sign 2 Heart suit 170 199 TEC Capital Greek Gamma 2 Spade suit 171 204 TEC Capital Greek Lambda 2 Left-and-right arrow 172 251 TEC Left arrow 0 Left arrow 173 094 SGA Circumflex Accent 1 Up arrow 174 253 TEC Right arrow 0 Right arrow 175 254 TEC Down Arrow 0 Down Arrow 176 102 SGS Degree Symbol 0 Degree Symbol 177 103 SGS Plus or Minus 0 Plus or Minus 178 034 SGA Double Quote 1 Double prime 179 122 SGS Greater-Equal 0 Greater-Equal 179 190 TEC Greater-Equal 0 Greater-Equal 180 203 TEC Multiplication symbol 0 Multiplication symbol 181 193 TEC Proportional-to 0 Proportional-to 182 239 TEC Partial differential sign 0 Partial differential sign 183 UNDEFINED 2 Large center dot 184 195 TEC Division 0 Division 185 124 SGS Not-Equal 0 Not-Equal 185 189 TEC Not-Equal 0 Not-Equal 186 207 TEC Identical-to sign 0 Identical-to sign 187 201 TEC Asymptotically equals 1 Approximately equal 188 114 SGS Horizontal Line - Scan 7 1 Ellipsis 189 120 SGS Vertical Line Centered 0 Up/Down arrow extension 189 166 TEC Vertical Line Centered 0 Up/Down Arrow extension 190 113 SGS Horizontal Line - Scan 5 0 Horizontal arrow extension 190 163 TEC Centered box horizonal line 0 Right/Left Arrow extension 191 104 SGS Display Ctrl NL 0 CRLF symbol ( <_| ) 192 UNDEFINED 2 Aleph 193 UNDEFINED 2 Fraktur I 194 UNDEFINED 2 Fraktur R 195 UNDEFINED 2 Script P 196 202 TEC Circled dot operator 2 Circled set/vector multiply 197 UNDEFINED 2 Circled set/vector summation 198 UNDEFINED 2 Null set, empty set 199 220 TEC Union 0 Union 200 221 TEC Intersection 0 Intersection 201 219 TEC Superset of 0 Superset of 202 UNDEFINED 2 Contains as subclass 203 UNDEFINED 2 Not contained as subclass 204 218 TEC Subset of 0 Subset of 205 UNDEFINED 2 Contained as subclass 206 UNDEFINED 2 Member of set 207 UNDEFINED 2 Not member of set 208 178 TEC Summation sign, lower half 1 Angle 209 197 TEC Nabla, Laplace operator 0 Nabla, Laplace operator 210 UNDEFINED 2 Registered, serif 211 216 TEC Capital Greek Xi 2 Copyright, serif 212 209 TEC Capital Greek Psi 2 Trademark, serif 213 208 TEC Capital Greek Pi 1 Product (big capital Pi) 214 161 TEC Radical sign 0 Radical sign 214 214 TEC Radical sign 0 Radical sign 215 126 SGS Centered Dot (small) 0 Centered Dot (small) 216 181 TEC Not sign 0 Not sign 216 224 TEC Not sign 0 Not sign 217 222 TEC Logical AND 0 Logical AND 218 223 TEC Logical OR 0 Logical OR 219 205 TEC If and only if sign (<=>) 0 If and only if sign (<=>) 220 UNDEFINED 2 Double left arrow 221 252 TEC Up arrow 2 Double up arrow 222 206 TEC Implies sign (=>) 0 Double right arrow 223 184 TEC Reverse question mark (UNDEFINED) 2 Double down arrow 223 185 TEC Reverse question mark (UNDEFINED) 2 Double down arrow 223 186 TEC Reverse question mark (UNDEFINED) 2 Double down arrow 223 187 TEC Reverse question mark (UNDEFINED) 2 Double down arrow 223 210 TEC Reverse question mark 2 Double down arrow 223 212 TEC Reverse question mark (UNDEFINED) 2 Double down arrow 223 213 TEC Reverse question mark (UNDEFINED) 2 Double down arrow 223 237 TEC Reverse question mark (UNDEFINED) 2 Double down arrow 223 245 TEC Reverse question mark (UNDEFINED) 2 Double down arrow 224 097 SGS Checkerboard (Error) 2 Diamond (hollow) 225 177 TEC Summation sign, upper half 1 Bra (large left angle bracket) 226 UNDEFINED 2 Registered, sans-serif 227 UNDEFINED 2 Copyright, sans-serif 228 UNDEFINED 2 Trademark, sans-serif 229 211 TEC Capital Greek Sigma 1 Summation (big capital Sigma) 230 171 TEC Extensible Left parenthesis top 0 Extensible left paren top 231 UNDEFINED 2 Extension for left paren 232 172 TEC Extensible Left parenthesis bot 0 Extensible left paren bottom 233 108 SGS Upper-Left Box Corner Centered 1 Left Bracket extension top 233 162 TEC Upper-Left Box Corner Centered 1 Left Bracket extension top 234 092 SGA Reverse Solidus, Backslash 2 Extension for left bracket 235 109 SGS Lower-Left Box Corner Centered 1 Left bracket extension bottom 236 167 TEC Extensible left bracket top 1 Extensible left brace top 237 175 TEC Extensible Left brace middle 0 Extensible left brace middle 238 168 TEC Extensible Left bracket bottom 1 Extensible left brace bot 239 UNDEFINED 2 Extension for left/right brace 240 UNDEFINED 2 UNDEFINED 241 183 TEC Ket, large right angle bracket 0 Ket 242 191 TEC Integral sign 0 Integral sign 243 164 TEC Integral top 0 Integral top 244 UNDEFINED 2 Extension for integral 245 165 TEC Integral bottom 0 Integral bottom 246 173 TEC Extensible Right parenthesis top 0 Extensible Right paren top 247 UNDEFINED 2 Extension for right paren 248 174 TEC Extensible Right parenthesis bot 0 Extensible Right paren bottom 249 107 SGS Upper-Right Box Corner Centered 1 Right Bracket extension Top 250 UNDEFINED 2 Extension for right bracket 251 106 SGS Lower-Right Box Corner Centered 1 Right Bracket extension Bottom 252 169 TEC Extensible Right bracket top 1 Extensible Right brace top 253 176 TEC Extensible Right brace middle 0 Extensible Right brace middle 254 170 TEC Extensible Right bracket bottom 1 Extensible Right brace bot 255 255 TEC (NONDISPLAY) 0 (NONDISPLAY) (the end)