SDMX Base Structure Module The base structure module contains the descriptions of base structural metadata constructs, such as item schemes, structures, and structure usages, as well as constructs reused by multiple types of structural components. ItemSchemeType is an abstract base type for all item scheme objects. It contains a collection of items. Concrete instances of this type should restrict the actual types of items allowed within the scheme. The isPartial, if true, indicates that only the relevant portion of the item scheme is being communicated. This is used in cases where a codelist is returned for a data structure in the context of a constraint. Item is an abstract element that serves as a substitution head for all items in an item scheme, including those items nested within other items. Concrete instances of this must use a concrete instance of ItemType. ItemBaseType is an abstract base type that forms the basis for the ItemType. It requires that at least an id be supplied for an item. ItemType is an abstract base type for all items with in an item scheme. Concrete instances of this type may or may not utilize the nested item, but if so should restrict the actual types of item allowed. UnnestedItemType is an abstract base type for all items with in an item scheme that do not contain nested items. StructureType is an abstract base type for all structure objects. Concrete instances of this should restrict to a concrete grouping. Grouping is an abstract element that serves as a substitution head for all structure groupings. Groupings contain a collection of component lists for a structure. Concrete instances of this must use a concrete instance of GroupingType. GroupType is an abstract base type for specific structure groupings. It contains a collection of component lists. Concrete instances of this should restrict to specific concrete component lists. ComponentList is an abstract element that serves as a substitution head for all component lists. Concrete instances of this must use a concrete instance of ComponentListType. ComponentListType is an abstract base type for all component lists. It contains a collection of components. Concrete types should restrict this to specific concrete components. Component is an abstract element that serves as a substitution head for all components. Concrete instances of this must use a concrete instance of ComponentType. ComponentBaseType is an abstract type that only serves the purpose of forming the base for the actual ComponentType. It only restricts the format of the id attribute to the NCNameIDType. The id attribute holds an explicit identification of the component. If this identifier is not supplied, then it is assumed to be the same as the identifier of the concept referenced from the concept identity. Because structures require that every component be given a unique identifier, it may be necessary to assign an explicit identifier when more than one component in a structure reference concepts with same identifier. It is important to note that this applies strictly to the identifier of concept and not the URN. Therefore if two concepts with the same identifier from different concept schemes are referenced in the same structure, one of the components will have to provide a unique explicit identifier. The type of this identifier is restricted to the common:NCNameIDType. This is necessary, since component identifiers are used to create XML elements and attributes in data and metadata structure specific schemas and therefore must be compliant with the NCName type in XML Schema (see common:NCNameIDType for further details). ComponentType is an abstract base type for all components. It contains information pertaining to a component, including an optional reference to a concept, an optional role played by the concept, an optional text format description, and an optional local representation. ConceptIdentity allows for the referencing of a concept in a concept scheme. The component takes its semantic from this concept, and if an id is not specified, it takes its identification as well. If a representation (LocalRepresentation) is not supplied, then the representation of the component is also inherited from the concept. Note that in the case of the component representation being inherited from the concept, the allowable representations for the component still apply. Therefore, if a component references a concept with a core representation that is not allowed for the concept, that representation must be locally overridden. For components which can specify a concept role, it is implied that the concept which is referenced also identifies a role for the component. LocalRepresentation references item schemes that may be used to create the representation of a component. The type of this must be refined such that a concrete item scheme reference is used. StructureUsageType is an abstract base type for all structure usages. It contains a reference to a structure. Concrete instances of this type should restrict the type of structure referenced. Structure references the structure (data structure or metadata structure definition) which the structure usage is based upon. Implementations will have to refine the type to use a concrete structure reference (i.e. either a data structure or metadata structure definition reference). RepresentationType is an abstract type that defines a representation. Because the type of item schemes that are allowed as the an enumeration vary based on the object in which this is defined, this type is abstract to force that the enumeration reference be restricted to the proper type of item scheme reference. TextFormat describes an uncoded textual format. Enumeration references an item scheme that enumerates the allowable values for this representation. EnumerationFormat describes the facets of the item scheme enumeration. This is for the most part, informational. The minOccurs attribute indicates the minimum number of value that must be reported for the component. The maxOccurs attribute indicates the maximum number of values that can be reported for the component. TextFormatType defines the information for describing a full range of text formats and may place restrictions on the values of the other attributes, referred to as "facets". SentinelValue defines a value that has a special meaning within the text format representation of a component. The textType attribute provides a description of the datatype. If it is not specified, any valid characters may be included in the text field (it corresponds to the xs:string datatype of W3C XML Schema) within the constraints of the facets. The isSequence attribute indicates whether the values are intended to be ordered, and it may work in combination with the interval, startValue, and endValue attributes or the timeInterval, startTime, and endTime, attributes. If this attribute holds a value of true, a start value or time and a numeric or time interval must supplied. If an end value is not given, then the sequence continues indefinitely. The interval attribute specifies the permitted interval (increment) in a sequence. In order for this to be used, the isSequence attribute must have a value of true. The startValue attribute is used in conjunction with the isSequence and interval attributes (which must be set in order to use this attribute). This attribute is used for a numeric sequence, and indicates the starting point of the sequence. This value is mandatory for a numeric sequence to be expressed. The endValue attribute is used in conjunction with the isSequence and interval attributes (which must be set in order to use this attribute). This attribute is used for a numeric sequence, and indicates that ending point (if any) of the sequence. The timeInterval attribute indicates the permitted duration in a time sequence. In order for this to be used, the isSequence attribute must have a value of true. The startTime attribute is used in conjunction with the isSequence and timeInterval attributes (which must be set in order to use this attribute). This attribute is used for a time sequence, and indicates the start time of the sequence. This value is mandatory for a time sequence to be expressed. The endTime attribute is used in conjunction with the isSequence and timeInterval attributes (which must be set in order to use this attribute). This attribute is used for a time sequence, and indicates that ending point (if any) of the sequence. The minLength attribute specifies the minimum and length of the value in characters. The maxLength attribute specifies the maximum length of the value in characters. The minValue attribute is used for inclusive and exclusive ranges, indicating what the lower bound of the range is. If this is used with an inclusive range, a valid value will be greater than or equal to the value specified here. If the inclusive and exclusive data type is not specified (e.g. this facet is used with an integer data type), the value is assumed to be inclusive. The maxValue attribute is used for inclusive and exclusive ranges, indicating what the upper bound of the range is. If this is used with an inclusive range, a valid value will be less than or equal to the value specified here. If the inclusive and exclusive data type is not specified (e.g. this facet is used with an integer data type), the value is assumed to be inclusive. The decimals attribute indicates the number of characters allowed after the decimal separator. The pattern attribute holds any regular expression permitted in the similar facet in W3C XML Schema. The isMultiLingual attribute indicates for a text format of type "string", whether the value should allow for multiple values in different languages. SentinelValueType defines the structure of a sentinel value. A sentinel is a value that has a special meaning within the text format representation of a component. The value is associated with a multi-lingual name and description. The sentinel value being described. BasicComponentTextFormatType is a restricted version of the TextFormatType that restricts the text type to the representations allowed for all components except for target objects. SimpleComponentTextFormatType is a restricted version of the BasicComponentTextFormatType that does not allow for multi-lingual values. CodedTextFormatType is a restricted version of the SimpleComponentTextFormatType that only allows factets and text types applicable to codes. Although the time facets permit any value, an actual code identifier does not support the necessary characters for time. Therefore these facets should not contain time in their values. CodeDataType is a restriction of the basic data types that are applicable to codes. Although some of the higher level time period formats are perimitted, it should be noted that any value which contains time (which includes a time zone offset) is not allowable as a code identifier. NonFacetedTextFormatType is a restricted version of the SimpleComponentTextFormatType that does not allow for any facets. TimeTextFormat is a restricted version of the SimpleComponentTextFormatType that only allows time based format and specifies a default ObservationalTimePeriod representation and facets of a start and end time.