IEEE 1484.11.3:2005 pdf free download – IEEE Standard for Learning Technology – Extensible Markup Language (XML) Schema Binding for Data Model for Content Object Communication
The w3C XML Schema definition language cannot specify whether a collection implemented withxs :sequence should be treated as a bag (unordered) or an array (ordered).However, it is possible insome cases to specify whether the items in the collection have to have different content, which is onecharacteristic of a set model. Implementers should refer to IEEE Std 1484.11.1-2004 to determine whether aparticular element defined as xs : sequence with a single element defined in the sequence should betreated as a bag, a set, or an array.As stated in w3C XML Schema Part 2, “The fact that this specificationdocs not define an order-relation for some datatype does not mean that some other application cannot treatthat datatype as being ordered by imposing its own order relation.”
Whenever an xs :sequence construct is defined as part of a type definition, the XSD defines an attributenamed collectionType.The value of this attribute is fixed as one of bag,array,or set.XMLSchema syntax does not allow the addition of this attribute for element sequences defined in an xs : groupconstruct. The collectionType attribute has no effect on XML validation, but it may be useful forapplications,because an XML Schema processor has to make the fixed attribute and its value available toapplications even if they are not explicitly specified in the COCD XML instance. This Standard does notdefine any conformance requirements regarding the use or interpretation of the collectionTypeattribute.
An SPM cannot be expressed in the W3C XML Schema definition language in any way that would allowautomatic validation of an SPM constraint as defined in the data model.Therefore, the XSD always specifiesmaxOccurm “unbounded” when the data model allows multiplicity, and it does not set a maxLengthattribute for other types for which an SPM is specified in the data model. Implementers should refer toIEEE Std 1484.11.1-2004 to determine the SPM that applies to a particular element.
Where possible, the XSD defines an attribute named spm. This attribute is added to several elements andtypes defined in the XSD with a fixed value that is the SPM value.However,XML Schema syntax does notallow the addition of this attribute for element sequences defined in an xs : group construct nor is thisattribute defined for string types that have to remain simple types,such as short and long identifiers. Thisattribute has no effect on XML validation, but it may be useful for applications, because an XML Schemaprocessor has to make the fixed attribute and its value available to applications even if they are not explicitlyspecified in the COCD XML instance. This Standard does not define any conformance requirementsregarding the use or interpretation of the spm attribute.