[XML-DEV Mailing List Archive Home] [By Thread] [By Date] [Recent Entries] [Reply To This Message] Re: XPath/XQuery - Typed Value Determination
On Thu, 20 Oct 2005, Alan Gutierrez wrote: > I'm confused by the wording of... > > http://www.w3.org/TR/xpath-datamodel/#TypedValueDetermination > > ...where it discusses the value value determination for lists. > > "For each of these lexical forms, the type of the corresponding > item is found in {item type definition}." > > I can't figure out if the {item type definition} is attached to > the list as a property, or an index property, or if it attached > to the item within the list. The mention of recursion implies > the latter. I think one would need a larger quote to understand the question...: "The types of the items in the typed value of a node are determined by a recursive process called typed value determination. This process begins with T, the schema type of the node itself, as represented in the PSVI. The type T has a variety, which is either atomic, union, or list. The typed value determination process is defined as follows: <skip other cases> - If the {variety} of T is list, the [schema normalized value] of the node is considered to be a space-separated list of lexical forms, each of which has its own type. For each of these lexical forms, the type of the corresponding item is found in {item type definition}. This type is then substituted for T, and the typed value determination process is invoked recursively for each member of the list." Brief answer: {item type definition} is a property of T, the schema's list _type_ that validated the value in question. It is not a property the list _value_. One could arrive to this understanding after meditating over WXS Part 2, 4.1.1 http://www.w3.org/TR/xmlschema-2/#rf-defn [I tried to find a description of Typed Value Determination in XQuery Formal Semantics, but apparently it just refers to the above-quoted definition (see 3.5.2, http://www.w3.org/TR/2005/WD-xquery-semantics-20050915/#id-typed-value) Too bad. I guess, the reason is that formalizing this notion would require formalizing most of WXS, which is any formalist's nightmare!] Vladimir
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