1624 2005-07-15 01:17:59 +0000 can type definitions be recursive? 2007-01-16 17:28:54 +0000 1 1 1 Unclassified XPath / XQuery / XSLT Formal Semantics 1.0 Last Call drafts PC Windows 2000 CLOSED FIXED P2 minor --- 1 fred.zemke simeon public-qt-comments oldest_to_newest 4700 0 fred.zemke 2005-07-15 01:17:59 +0000 2.4.4 Top level definitions Are recursive types permitted? I don't see a prohibition, and it seems that they are necessary to define certain types, for example, the ability to have an arbitrary binary tree in XML would require a type such as define type node as { (element left of type node, element right of type node) ? } It would be good to state this explicitly. On the other hand, setion 8.1.1 "Derived from" under "Note" second sentence says "...no cycles are allowed in derivation by restriction or extension". It would be good to include this prohibition in section 2.4.4. Note, though that the definition of xs:anyType in section 3.5.1 is recursive and is a definition by restriction (it says that xs:anyType is a restriction of itself). This example contradicts the prohibition on cycles in derivation by restriction. Perhaps the prohibition should be worded, "Except for the definition of xs:anyType, cycles are not permitted in definition by restriction or extension". 4882 1 simeon 2005-07-19 17:01:09 +0000 I believe this is editorial. We should refer to the rules for this in XML Schema. - Jerome 9230 2 simeon 2006-04-13 19:08:40 +0000 Added a sentence in that Section to indicate that recursive types can be defined, according to the result specified in XML Schema. - Jerome