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Substitution groups vs. type inheritance
- From: Julio Andrade <email@example.com>
- To: firstname.lastname@example.org
- Date: Thu, 14 Jun 2001 11:45:14 -0700
substitution groups and type inheritance seem to provide similar
capabilities. What are differences? When should I use one
or the other?
both are substitution mechanisms
use instance of derived where base expected/use substitute
where head expected
the substitution is restricted to one to many
one base, multiple derived/one head, multiple substitutes
substitution is restricted to same or derived type in both cases
(if the type differs, to be able to use substitution groups
you must have defined a type hierarchy anyways!?)
both can be defined across namespaces
in substitution groups you are working with elements, versus types
in type inheritance (not sure about implications of this).
substitution groups are based on global types + references in
local elements. This makes for ugly instance documents if using
(I searched the archives, but couldn't find a discussion on this.
If I missed something pl. send a URL)