CODEWITHSUNDEEP
xmlxsdschemarestriction
meta_leap
meta_leap

Reputation: 2185

In XSD, what's the meaning/purpose of a simpleType/restriction/simpleType element?

In an XML Schema Definition (XSD) document, according to this, one can have a simpleType element containing a restriction element that may have another simpleType element.

I have browsed many restriction / simpleType related pages including the W3 Schema Primer, yet I have not been able to find a simple explanation of how this should be interpreted by an XSD processor. I get what a simpleType is, I get most of its possible restrictions, but I can't quite figure out what a simpleType/restriction/simpleType construction is supposed to mean. How is this commonly / typically used by schema designers?

Upvotes: 1

Views: 182

Answers (2)

13ren
13ren

Reputation: 12187

It's an alternative to base="". Similar to an <element> having either type="" or a <complexType> (but not both nor neither).

{base type definition} The Simple Type Definition component resolved to by the actual value of the base [attribute] or the <simpleType> [children], whichever is present.

http://www.w3.org/TR/2001/REC-xmlschema-2-20010502/#derivation-by-restriction

Upvotes: 2

Michael Kay
Michael Kay

Reputation: 163458

XSD generally allows one definition to refer to another either by name (ref=NNNN), or by embedding the other definition inline. I can't see any strong reason use this mechanism for defining the base type of a type derived by restriction, but it's there for generality and consistency. (And just because I can't see a use for it doesn't mean there isn't one...)

Upvotes: 2

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