FSC-0031 May 1, 1989 EchoMail ^aEID: Dup-Checking with Linked Replies A Proposal To The FidoNet Technical Standards Committee Currently, no universal methodology for implementing echomail duplicate message checking exists. One thing is certain - they will only increase in number as the shear volume of echomail is increasing every day! In order to catch the highest percentage of duplicates possible it is desirable to utilize a system which actually tags each of the messages themselves with a distinct messages identifier to be used to check against an existing database of all previous messages' identifiers. In practice, this is not possible, but we can limit the number of previous identifiers kept so that processing is quick but still almost certain to eliminate any duplicate messages. This also provides an easy method of linking replies to their original message by appending the previous identifier. Using a linked reply technique allows easy relinking of the messages to the original message, assuming it still exists. This proposed ^aEID: kludge line specifications are as follows: 1) A 16-bit CRC followed by a 32-bit DOS file date/time stamp. 2) The 16-bit CRC is calculated by first CRC'ing all but the first 11 (static) characters of the origin line, followed by the first two "words" of the from name, the first two words of the to name, and the first 25 characters of the subject line after stripping leading occurances of "Re: " sequences. Notes: You must always upper-case the to/from/subject fields, as some current processors will change the case of that text. Using only the first two words of the from and to names will eliminate the potential problem when some processors add the " of xxx/yyy" to the end. Stripping all leading occurances of the "Re: " in the subject field is also done to eliminate the possibility of changed subject lines not matching with the original message, which is also the reason for limiting the length of that field to the first 25 bytes (after taking off all the "Re: " sequences), because adding the leading "Re: " may force characters out (because they are beyond the 72-character field limit). When you must add an EID line for a message which is not local, you have to zero the seconds field before creating the 32-bit time stamp - some processors eliminate this information! This limitation can be overcome if most editors insert them at the time they are written. Automatic reply linking ========= ===== ======= When replying to a message with an ^aEID: line, extend the new ^aEID: with the ^aEID: fields of the original message. The new line would look like this: ^aEID: xxxx yyyyzzzz uuuu vvvvwwww Where 'uuuu vvvvwwww' is the Eid information of the original message. Only one previous message's information is retained.