Links between objects

Hello Schematologists,

I've some experience in describing models using EXPRESS (and also
XML-Schema). The one thing I miss most in Schema is a simple way to
describe a link between two (or more) different (or same) type of objetcs.

In EXPRESS you can write something like:

ENTITY parent
   children : LIST [0..?] OF child;
END_ENTITY;

ENTITY child
END_ENTITY;

Now assume I want to express that the child has a 'backward' relationship
to it's parents, a so called inverse:

ENTITY child
INVERSE
   myparent : parent for children;
END_ENTITY;

For a model often a hint to a semi optimal solution but sometimes necessary
is a so called select:

ENTIY boy
END_ENTITY;

ENTITY girl
END_ENTITY;

TYPE child_select = SELCECT(boy, girl); END_TYPE;

ENTITY parent
   children : LIST [0..?] OF child_select;
END_ENTITY;

I like this elegant solutions (for describing relationships) and did not
found anything comparable in Schema.

You all did a very good job with the first version, good luck for version
1.1.

Regards
Stefan Romainczyk

----------------------------------------------
Stefan Romainczyk
Dipl.- Ing.

National Instruments Engineering GmbH & Co. KG
Pascalstr. 18
D-52076 Aachen

Phone +49-(2408) 1438-535
Fax +49-(2408) 1438-190
www.ni.com