Joined: 22 Apr 2006 Posts: 6258 Location: Mumbai, India
That is something specific to your shop, it might be a standard at your shop to use Julian date (as Enrico has said), such as in this new shop I'm at, they use a Julian date of the form CCYYDDD, e.g. 2009111.
Actually, IMS has no data types - so dates etc will probably be in character format (with many invalid dates - at least we have in our IMS databases). On the other hand, probably because, as IMS is in use since around 1966, probably no one has thought about Y2K at that time and an obvious choice must have been Julian dates (for a four-digit year) instead of gregorian so that you can right away know what day of year you are at...just a thought. However, the dates you show have only 2-digits year - most probably there had been some work around in programs dealing with these dates.
how to diffrentiate this date I.E if it is 91212 year is 2009,1999,1989..
A segment may be defined with a size of some bytes(say 40) but only define one field that as a key field that you can use to find the segment when performing queries. IMS will retrieve and save all 40 bytes as directed by a program but may not understand (or care) what the other bytes represent. In practice, often all data in a segment may map to a COBOL copybook and that where yo understand what date it is.