Chris, That is very similar to the approach I took with an open source X12 parser/translator project. Without looking at the code I think I might have checked beyond the 7th position for additional element separators, but that level of thoroughness would probably screen out an extremely small number of cases in actual practice.
Mike ----------------------------------------- Michael C. Rawlins, Rawlins EC Consulting www.rawlinsecconsulting.com On 7/21/2010 5:26 AM, Chris Johnson wrote: > > The recent thread about problems with interchange recognition in eVision > made me think about what one should do to recognise an ISA segment. As > an EDI software coder this can be an acute problem when trying to > extract EDI from the body of an email, particularly when the mailbox is > not used exclusively for EDI traffic (it does happen), but there are > other noisy transmission methods for which it is relevant. > > You need to strike a balance between selection criteria which are too > weak (if you just look for "ISA" there is a real risk of aliasing with > general text), and too stringent (if you test the position and value of > every delimiter then you may ignore a badly formed segment which should > properly have been analysed and reported on by the EDI system). > > We require that the interchange start with "ISA" and that the fourth and > seventh characters be the same. If this condition is satisfied then the > parser is invoked to analyse the character stream as an X12 interchange. > This has worked for us for over fifteen years, but we do not have to > deal with much X12! I wondered what the thoughts of the list members > were about this? > > Regards > Chris > > -- > Chris Johnson mobile:+44 (0)7785 302122 Fax: +44 (0)870 0519 818 > EDI website http://www.edimatrix.co.uk > EDIMatrix Ltd work: 0845 126 0680 or +44 20 8778 1402 > Registered in UK no. 2777624 Reg.Office: 34 Sydenham Rd, London SE26 5QF > > ------------------------------------ ... Please use the following Message Identifiers as your subject prefix: <SALES>, <JOBS>, <LIST>, <TECH>, <MISC>, <EVENT>, <OFF-TOPIC> Job postings are welcome, but for job postings or requests for work: <JOBS> IS REQUIRED in the subject line as a prefix.Yahoo! Groups Links <*> To visit your group on the web, go to: http://groups.yahoo.com/group/EDI-L/ <*> Your email settings: Individual Email | Traditional <*> To change settings online go to: http://groups.yahoo.com/group/EDI-L/join (Yahoo! ID required) <*> To change settings via email: [email protected] [email protected] <*> To unsubscribe from this group, send an email to: [email protected] <*> Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/
