date effectivity

I was wondering how to represent an end date effectivity when the start

date effectivity is not known. E.g. A feedback record is reporting the fact that a component is removed

from an aircraft, but I have no idea when it was installed, but I know when I took it off.

The EXPRESS forces a start effectivity

ENTITY Dated_effectivity

SUBTYPE OF (Effectivity);

start_bound : date_or_event;

end_bound : OPTIONAL date_or_event;

END_ENTITY;

I can get around the problem in a feedback activity by classifying the activity_actual as a removal or installation activity.

But this does not seem the safest approach.

One suggestion is to use a dummy date 1900-01-01

Another is to raise a SEDS against the Date_effectivity to allow start_bound to be optional – that will take some time

Any thoughts?

Regards
Rob

-------------------------------------------
Rob Bodington
Eurostep Limited
Web Page: http://www.eurostep.com http://www.share-a-space.com
Email: Rob.Bodington@eurostep.com
Phone: +44 (0)1452 810 960
Mobile: +44 (0)7796 176 401

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