- ( , ). , , , . , "" "" " " ( ). - , . ERwin :
(, , / , );
;
() ;
(cardinality);
(null) .
, . , , . .
, , . , , .
ERwin , . ; - . .
. .
. ERwin , .. , . . , " " " -" " -". "" (" ") .
- .
. , , 1:n.
ERwin IDEF1X 4 n, : , ( ); ; N, N - .
(NULL) ERwin .
, , , IE . 1.
.1. IE
"", . ( ) ERwin (constraint) .