Object models for computer aided design

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37 c􁪽􋵥er2􁪽􋵥e a􁪽􋵥 enter;rise (e.g. an insurance corr.􁪽􋵡ar.y). The 􁪽􋵥e5earct and develop􁪽􋵥e􁪽􋵴t 􁪽􋵮n data base systems is :or.cEr􁪽􋵥e6 􁪽􋵩i:􁪽􋵧 general 􁪽􋴰06el􁪽􋵮ng considerations. In a data base sy5􁪽􋵥e􁪽􋴬, one needs a mechanis􁪽􋵴 to define the structure of :􁪽􋵥e infcr􁪽􋵡ation:n the data base and procedures for 􁪽􋵡a􁪽􋴺:;􁪽􋵬la:􁪽􋵮n; t􁪽􋵩is infor􁪽􋵡ation wh􁪽􋵣ch sat􁪽􋵳sfy the needs for e :: fee t 􁪽􋵶 v e :-: e s s , e f f i c i e n c y, c I a r i t y, and fl e x i t- i h t y • The purpose of 􁪽􋴰05t commercial data base systems is to centralize and organize the infor􁪽􋵡ation needed to 􁪽􋵲rir:2ry context business data processin,? 􁪽􋴿?;licaticns and Cobol is the most COffimon host 1􁪽􋴚􁪽􋵧guage for :􁪽􋵯ose !y5te􁪽􋵳s 􁪽􋵨hich are not self contained. Cobol-like reccr􁪽􋴚 􁪽􋴺:r􁪽􋴺:t􁪽􋵲res are often used as the f u n C 2: IT. e 􁪽􋵴 tal cbjects which are 􁪽􋵡anipu12ted by the a' - I- - O'-C base system. TM􁪽􋵳se re􁪽􋴺:r6s are then organized into either tree structures, in the hierarchic systerr.s, or 'interconnected 􁪽􋵲r2􁪽􋴚􁪽􋴡 !􁪽􋵲r􁪽􋵣ctures in the network systems. 3.3.􁪽􋴚 􁪽􋵩i􁪽􋵲r2rchic Data EaSE Systerrs :te 􁪽􋵡ata base 2Fpears to the user of a hierarc􁪽􋵩ic systerr as a forest of n-ary trees. The 􁪽􋵯odel m􁪽􋵩it be