RFC 4912
Abstract Syntax Notation X (ASN.X)
Pages: 165
Experimental
Experimental
Part 4 of 6 – Pages 66 to 93
9. Translation of Object Classes
The translation of an ObjectClass is the translation of the DefinedObjectClass, ObjectClassDefn, or ParameterizedObjectClass in the ObjectClass. The translation of a ParameterizedObjectClass is described in Section 13.9.1. DefinedObjectClass Translation
If a DefinedObjectClass is an objectclassreference (not a DummyReference), an ExternalObjectClassReference, or a UsefulObjectClassReference, then the translation of the
DefinedObjectClass is either the attribute form translation of an object class reference, or the element form translation of an object class reference. The attribute form translation of an object class reference is an attribute item with the [local name] "class". The [normalized value] of this attribute item is a qualified name for the expanded name of the referenced object class definition (see Section 5.1). In the case of a UsefulObjectClassReference, the namespace name of the expanded name is "urn:ietf:params:xml:ns:asnx", and the local name is either "TYPE-IDENTIFIER" or "ABSTRACT-SYNTAX", as the case may be. The attribute form translation SHALL NOT be used if the expanded name is not distinct with respect to the current module and the modules referenced by its <import> element items (see Section 5.1). Otherwise, the translator is free to choose either the attribute form or element form translation for an object class reference. The element form translation of an object class reference is an element item with the [local name] "class". An element item with the [local name] "annotation" MAY be added to the [children] of the <class> element item. An attribute item with the [local name] "ref" SHALL be added to the [attributes] of the <class> element item. The [normalized value] of this attribute item is a qualified name for the expanded name of the referenced object class definition. In the case of a UsefulObjectClassReference, the namespace name of the expanded name is "urn:ietf:params:xml:ns:asnx" and the local name is either "TYPE-IDENTIFIER" or "ABSTRACT-SYNTAX", as the case may be. If the expanded name is not distinct with respect to the current module and the modules referenced by its <import> element items, then an attribute item with the [local name] "context" SHALL be added to the [attributes] of the <class> element item; otherwise, if the module containing the referenced object class definition has a schema identity URI, then an attribute item with the [local name] "context" MAY be added to the [attributes] of the <class> element item. The [normalized value] of this attribute item is the schema identity URI of the module containing the referenced object class definition. Aside: If a reference name is not distinct, then the module containing the referenced definition must have a schema identity URI (see Section 5.1). The translation of the DefinedObjectClass is the same whether the object class definition is referenced by an objectclassreference or an ExternalObjectClassReference. If a DefinedObjectClass is a DummyReference, then the translation of the DefinedObjectClass is the translation of the DummyReference (see Section 13).
9.2. ObjectClassDefn Translation
The translation of an ObjectClassDefn is an element item with the [local name] "class". An element item with the [local name] "annotation" MAY be added to the [children] of the <class> element item. The translation of each FieldSpec in the ObjectClassDefn SHALL be appended to the [children] of the <class> element item. The translation of a FieldSpec is the translation of the TypeFieldSpec, FixedTypeValueFieldSpec, VariableTypeValueFieldSpec, FixedTypeValueSetFieldSpec, VariableTypeValueSetFieldSpec, ObjectFieldSpec, or ObjectSetFieldSpec in the FieldSpec.9.2.1. TypeFieldSpec Translation
The translation of a TypeFieldSpec where the TypeOptionalitySpec is absent is an element item with the [local name] "typeField". The translation of a TypeFieldSpec with a TypeOptionalitySpec of the "OPTIONAL" form is an element item with the [local name] "optional". An element item with the [local name] "typeField" SHALL be added to the [children] of the <optional> element item. The translation of a TypeFieldSpec with a TypeOptionalitySpec of the "DEFAULT Type" form is an element item with the [local name] "optional". An element item with the [local name] "typeField" SHALL be added to the [children] of the <optional> element item. An element item with the [local name] "default" SHALL be appended to the [children] of the <optional> element item. The translation of the Type in the TypeOptionalitySpec SHALL be added to the [children] or [attributes] of the <default> element item. An attribute item with the [local name] "name" SHALL be added to the [attributes] of the <typeField> element item. The [normalized value] of this attribute item is the typefieldreference in the TypeFieldSpec, without the ampersand character ('&', U+0026). An element item with the [local name] "annotation" MAY be added to the [children] of the <typeField> element item. Example CLASS { &One, &Two OPTIONAL, &Three DEFAULT OBJECT IDENTIFIER }
<class>
<typeField name="One"/>
<optional>
<typeField name="Two"/>
</optional>
<optional>
<typeField name="Three"/>
<default type="asnx:OBJECT-IDENTIFIER"/>
</optional>
</class>
9.2.2. FixedTypeValueFieldSpec Translation
The translation of a FixedTypeValueFieldSpec where the
ValueOptionalitySpec is absent is an element item with the
[local name] "valueField".
The translation of a FixedTypeValueFieldSpec with a
ValueOptionalitySpec of the "OPTIONAL" form is an element item with
the [local name] "optional". An element item with the [local name]
"valueField" SHALL be added to the [children] of the <optional>
element item.
The translation of a FixedTypeValueFieldSpec with a
ValueOptionalitySpec of the "DEFAULT Value" form is an element item
with the [local name] "optional". An element item with the
[local name] "valueField" SHALL be added to the [children] of the
<optional> element item. An element item with the [local name]
"default" SHALL be appended to the [children] of the <optional>
element item. The translation of the Value in the
ValueOptionalitySpec SHALL be added to the [children] or [attributes]
of the <default> element item.
An attribute item with the [local name] "name" SHALL be added to the
[attributes] of the <valueField> element item. The
[normalized value] of this attribute item is the valuefieldreference
in the FixedTypeValueFieldSpec, without the ampersand character ('&',
U+0026). If the "UNIQUE" keyword is present, then an attribute item
with the [local name] "unique" and [normalized value] "true" or "1"
SHALL be added to the [attributes] of the <valueField> element item;
otherwise, an attribute item with the [local name] "unique" and
[normalized value] "false" or "0" MAY be added to the [attributes] of
the <valueField> element item. An element item with the [local name]
"annotation" MAY be added to the [children] of the <valueField>
element item. The translation of the Type in the
FixedTypeValueFieldSpec SHALL be added to the [children] or
[attributes] of the <valueField> element item.
Example
CLASS {
&one OBJECT IDENTIFIER UNIQUE,
&two BOOLEAN OPTIONAL,
&three INTEGER DEFAULT 0
}
<class>
<valueField name="one" unique="true"
type="asnx:OBJECT-IDENTIFIER"/>
<optional>
<valueField name="two" type="asnx:BOOLEAN"/>
</optional>
<optional>
<valueField name="three" type="asnx:INTEGER"/>
<default literalValue="0"/>
</optional>
</class>
9.2.3. FixedTypeValueSetFieldSpec Translation
The translation of a FixedTypeValueSetFieldSpec where the
ValueSetOptionalitySpec is absent is an element item with the
[local name] "valueSetField".
The translation of a FixedTypeValueSetFieldSpec with a
ValueSetOptionalitySpec of the "OPTIONAL" form is an element item
with the [local name] "optional". An element item with the
[local name] "valueSetField" SHALL be added to the [children] of the
<optional> element item.
The translation of a FixedTypeValueSetFieldSpec with a
ValueSetOptionalitySpec of the "DEFAULT ValueSet" form is an element
item with the [local name] "optional". An element item with the
[local name] "valueSetField" SHALL be added to the [children] of the
<optional> element item. An element item with the [local name]
"default" SHALL be appended to the [children] of the <optional>
element item. The translation of the ValueSet in the
ValueSetOptionalitySpec SHALL be added to the [children] of the
<default> element item.
An attribute item with the [local name] "name" SHALL be added to the
[attributes] of the <valueSetField> element item. The
[normalized value] of this attribute item is the
valuesetfieldreference in the FixedTypeValueSetFieldSpec, without the
ampersand character ('&', U+0026). An element item with the
[local name] "annotation" MAY be added to the [children] of the
<valueSetField> element item. The translation of the Type in the
FixedTypeValueSetFieldSpec SHALL be added to the [children] or
[attributes] of the <valueSetField> element item.
Example
CLASS {
&One UTF8String,
&Two BOOLEAN OPTIONAL,
&Three INTEGER DEFAULT { 1 | 2 }
}
<class>
<valueSetField name="One" type="asnx:UTF8String"/>
<optional>
<valueSetField name="Two" type="asnx:BOOLEAN"/>
</optional>
<optional>
<valueSetField name="Three" type="asnx:INTEGER"/>
<default>
<valueSet>
<union>
<literalValue>1</literalValue>
<literalValue>2</literalValue>
</union>
</valueSet>
</default>
</optional>
</class>
9.2.4. VariableTypeValueFieldSpec Translation
The translation of a VariableTypeValueFieldSpec where the
ValueOptionalitySpec is absent is an element item with the
[local name] "valueField".
The translation of a VariableTypeValueFieldSpec with a
ValueOptionalitySpec of the "OPTIONAL" form is an element item with
the [local name] "optional". An element item with the [local name]
"valueField" SHALL be added to the [children] of the <optional>
element item.
The translation of a VariableTypeValueFieldSpec with a
ValueOptionalitySpec of the "DEFAULT Value" form is an element item
with the [local name] "optional". An element item with the
[local name] "valueField" SHALL be added to the [children] of the
<optional> element item. An element item with the [local name]
"default" SHALL be appended to the [children] of the <optional>
element item. The translation of the Value in the
ValueOptionalitySpec SHALL be added to the [children] or [attributes]
of the <default> element item.
An attribute item with the [local name] "name" SHALL be added to the
[attributes] of the <valueField> element item. The
[normalized value] of this attribute item is the valuefieldreference
in the VariableTypeValueFieldSpec, without the ampersand character
('&', U+0026). An element item with the [local name] "annotation"
MAY be added to the [children] of the <valueField> element item. An
element item with the [local name] "typeFromField" SHALL be appended
to the [children] of the <valueField> element item. The translation
of the FieldName in the VariableTypeValueFieldSpec SHALL be added to
the [children] or [attributes] of the <typeFromField> element item.
Example
CLASS {
&Syntax DEFAULT INTEGER,
&one &Syntax,
&two &Syntax OPTIONAL,
&three &Syntax DEFAULT 0
}
<class>
<optional>
<typeField name="Syntax"/>
<default type="asnx:INTEGER"/>
</optional>
<valueField name="one">
<typeFromField fieldName="Syntax"/>
</valueField>
<optional>
<valueField name="two">
<typeFromField fieldName="Syntax"/>
</valueField>
</optional>
<optional>
<valueField name="three">
<typeFromField fieldName="Syntax"/>
</valueField>
<default literalValue="0"/>
</optional>
</class>
9.2.5. VariableTypeValueSetFieldSpec Translation
The translation of a VariableTypeValueSetFieldSpec where the ValueSetOptionalitySpec is absent is an element item with the [local name] "valueSetField". The translation of a VariableTypeValueSetFieldSpec with a ValueSetOptionalitySpec of the "OPTIONAL" form is an element item with the [local name] "optional". An element item with the [local name] "valueSetField" SHALL be added to the [children] of the <optional> element item. The translation of a VariableTypeValueSetFieldSpec with a ValueSetOptionalitySpec of the "DEFAULT ValueSet" form is an element item with the [local name] "optional". An element item with the [local name] "valueSetField" SHALL be added to the [children] of the <optional> element item. An element item with the [local name] "default" SHALL be appended to the [children] of the <optional> element item. The translation of the ValueSet in the ValueSetOptionalitySpec SHALL be added to the [children] of the <default> element item. An attribute item with the [local name] "name" SHALL be added to the [attributes] of the <valueSetField> element item. The [normalized value] of this attribute item is the valuesetfieldreference in the VariableTypeValueSetFieldSpec, without the ampersand character ('&', U+0026). An element item with the [local name] "annotation" MAY be added to the [children] of the <valueSetField> element item. An element item with the [local name] "typeFromField" SHALL be appended to the [children] of the <valueSetField> element item. The translation of the FieldName in the VariableTypeValueSetFieldSpec SHALL be added to the [children] or [attributes] of the <typeFromField> element item. Example CLASS { &Syntax DEFAULT INTEGER, &One &Syntax, &Two &Syntax OPTIONAL, &Three &Syntax DEFAULT { 1 | 2 } } <class> <optional> <typeField name="Syntax"/> <default type="asnx:INTEGER"/> </optional>
<valueSetField name="One">
<typeFromField fieldName="Syntax"/>
</valueSetField>
<optional>
<valueSetField name="Two">
<typeFromField fieldName="Syntax"/>
</valueSetField>
</optional>
<optional>
<valueSetField name="Three">
<typeFromField fieldName="Syntax"/>
</valueSetField>
<default>
<valueSet>
<union>
<literalValue>1</literalValue>
<literalValue>2</literalValue>
</union>
</valueSet>
</default>
</optional>
</class>
9.2.6. FieldName Translation
The translation of a FieldName is either, at the translator's option,
an attribute item with the [local name] "fieldName" added to the
[attributes] of the enclosing element item, or an element item with
the [local name] "fieldName" appended to the [children] of the
enclosing element item.
The [normalized value] of the fieldName attribute item is a solidus
('/', U+002F) separated list of the PrimitiveFieldName instances in
the FieldName, without the ampersand characters ('&', U+0026).
Leading and/or trailing white space characters MAY be added to the
[normalized value] of the attribute item. White space characters MAY
be added immediately before and/or after any solidus character ('/',
U+002F) in the [normalized value].
The [children] property of the <fieldName> element item is set to the
sequence of character items for a solidus ('/', U+002F) separated
list of the PrimitiveFieldName instances in the FieldName, without
the ampersand characters ('&', U+0026). Leading and/or trailing
white space character items MAY be added to the [children] of the
<fieldName> element item. White space character items MAY be added
immediately before and/or after any character item for the solidus
character ('/', U+002F).
Example
&Linked.&ArgumentType
<fieldName>Linked/ArgumentType</fieldName>
9.2.7. ObjectFieldSpec Translation
The translation of an ObjectFieldSpec where the ObjectOptionalitySpec
is absent is an element item with the [local name] "objectField".
The translation of an ObjectFieldSpec with an ObjectOptionalitySpec
of the "OPTIONAL" form is an element item with the [local name]
"optional". An element item with the [local name] "objectField"
SHALL be added to the [children] of the <optional> element item.
The translation of an ObjectFieldSpec with an ObjectOptionalitySpec
of the "DEFAULT Object" form is an element item with the [local name]
"optional". An element item with the [local name] "objectField"
SHALL be added to the [children] of the <optional> element item. An
element item with the [local name] "default" SHALL be appended to the
[children] of the <optional> element item. The translation of the
Object in the ObjectOptionalitySpec SHALL be added to the [children]
or [attributes] of the <default> element item.
An attribute item with the [local name] "name" SHALL be added to the
[attributes] of the <objectField> element item. The
[normalized value] of this attribute item is the objectfieldreference
in the ObjectFieldSpec, without the ampersand character ('&',
U+0026). An element item with the [local name] "annotation" MAY be
added to the [children] of the <objectField> element item. The
translation of the DefinedObjectClass in the ObjectFieldSpec SHALL be
added to the [children] or [attributes] of the <objectField> element
item.
Example
CLASS {
&one TYPE-IDENTIFIER,
&two ABSTRACT-SYNTAX OPTIONAL,
&three TYPE-IDENTIFIER DEFAULT myObject
}
<class>
<objectField name="one" class="asnx:TYPE-IDENTIFIER"/>
<optional>
<objectField name="two" class="asnx:ABSTRACT-SYNTAX"/>
</optional>
<optional>
<objectField name="three" class="asnx:TYPE-IDENTIFIER"/>
<default object="tns:myObject"/>
</optional>
</class>
9.2.8. ObjectSetFieldSpec Translation
The translation of an ObjectSetFieldSpec where the
ObjectSetOptionalitySpec is absent is an element item with the
[local name] "objectSetField".
The translation of an ObjectSetFieldSpec with an
ObjectSetOptionalitySpec of the "OPTIONAL" form is an element item
with the [local name] "optional". An element item with the
[local name] "objectSetField" SHALL be added to the [children] of the
<optional> element item.
The translation of an ObjectSetFieldSpec with an
ObjectSetOptionalitySpec of the "DEFAULT ObjectSet" form is an
element item with the [local name] "optional". An element item with
the [local name] "objectSetField" SHALL be added to the [children] of
the <optional> element item. An element item with the [local name]
"default" SHALL be appended to the [children] of the <optional>
element item. The translation of the ObjectSet in the
ObjectSetOptionalitySpec SHALL be added to the [children] or
[attributes] of the <default> element item.
An attribute item with the [local name] "name" SHALL be added to the
[attributes] of the <objectSetField> element item. The
[normalized value] of this attribute item is the
objectsetfieldreference in the ObjectSetFieldSpec, without the
ampersand character ('&', U+0026). An element item with the
[local name] "annotation" MAY be added to the [children] of the
<objectSetField> element item. The translation of the
DefinedObjectClass in the ObjectSetFieldSpec SHALL be added to the
[children] or [attributes] of the <objectSetField> element item.
Example
CLASS {
&One TYPE-IDENTIFIER,
&Two ABSTRACT-SYNTAX OPTIONAL,
&Three TYPE-IDENTIFIER DEFAULT { myObject }
}
<class>
<objectSetField name="One" class="asnx:TYPE-IDENTIFIER"/>
<optional>
<objectSetField name="Two" class="asnx:ABSTRACT-SYNTAX"/>
</optional>
<optional>
<objectSetField name="Three" class="asnx:TYPE-IDENTIFIER"/>
<default>
<objectSet>
<object ref="tns:myObject"/>
</objectSet>
</default>
</optional>
</class>
10. Translation of Objects
The translation of an Object is the translation of the DefinedObject,
ObjectDefn, ObjectFromObject, or ParameterizedObject in the Object.
The translation of a ParameterizedObject is described in Section 13.
10.1. DefinedObject Translation
If a DefinedObject is an objectreference (not a DummyReference) or an
ExternalObjectReference, then the translation of the DefinedObject is
either the attribute form translation of an object reference, or the
element form translation of an object reference.
The attribute form translation of an object reference is an attribute
item with the [local name] "object". The [normalized value] of this
attribute item is a qualified name for the expanded name of the
referenced object definition (see Section 5.1). The attribute form
translation SHALL NOT be used if this expanded name is not distinct
with respect to the current module and the modules referenced by its
<import> element items (see Section 5.1).
The element form translation of an object reference is an element
item with the [local name] "object". An element item with the
[local name] "annotation" MAY be added to the [children] of the
<object> element item. An attribute item with the [local name] "ref"
SHALL be added to the [attributes] of the <object> element item. The
[normalized value] of this attribute item is a qualified name for the
expanded name of the referenced object definition. If this expanded
name is not distinct with respect to the current module and the
modules referenced by its <import> element items, then an attribute
item with the [local name] "context" SHALL be added to the
[attributes] of the <object> element item; otherwise, if the module
containing the referenced object definition has a schema identity
URI, then an attribute item with the [local name] "context" MAY be
added to the [attributes] of the <object> element item. The
[normalized value] of this attribute item is the schema identity URI
of the module containing the referenced object definition.
Aside: If a reference name is not distinct, then the module
containing the referenced definition must have a schema identity
URI (see Section 5.1).
The translation of the DefinedObject is the same whether the object
definition is referenced by an objectreference or an
ExternalObjectReference.
Usually the translator is free to choose either the attribute form or
element form translation for an object reference; however, in some
contexts the attribute form is explicitly disallowed.
If a DefinedObject is a DummyReference, then the translation of the
DefinedObject is the translation of the DummyReference (see
Section 13).
10.2. ObjectDefn Translation
An ObjectDefn that is a DefinedSyntax is first converted to the
equivalent DefaultSyntax and then translated.
The translation of an ObjectDefn is an element item with the
[local name] "object". An element item with the [local name]
"annotation" MAY be added to the [children] of the <object> element
item. The translation of each FieldSetting in the DefaultSyntax in
the ObjectClassDefn SHALL be appended to the [children] of the
<object> element item.
The translation of a FieldSetting is an element item with the
[local name] "field". An attribute item with the [local name] "name"
SHALL be added to the [attributes] of the <field> element item. The
[normalized value] of this attribute item is the PrimitiveFieldName
in the FieldSetting, without the ampersand character ('&', U+0026).
The translation of the Type, Value, ValueSet, Object, or ObjectSet in
the Setting in the FieldSetting SHALL be added to the [children] or
[attributes] of the <field> element item.
Example
-- This is the governing object class.
ONE-OF-EVERYTHING ::= CLASS {
&One,
&two INTEGER,
&Three INTEGER,
&four TYPE-IDENTIFIER,
&Five TYPE-IDENTIFIER
}
<namedClass name="ONE-OF-EVERYTHING">
<class>
<typeField name="One"/>
<valueField name="two" type="asnx:INTEGER"/>
<valueSetField name="Three" type="asnx:INTEGER"/>
<objectField name="four" class="asnx:TYPE-IDENTIFIER"/>
<objectSetField name="Five" class="asnx:TYPE-IDENTIFIER"/>
</class>
</namedClass>
mixedBag ONE-OF-EVERYTHING ::= {
&One BOOLEAN,
&two 99,
&Three { 1 | 2 },
&four myObject,
&Five { myObject }
}
<namedObject name="mixedBag" class="tns:ONE-OF-EVERYTHING">
<object>
<field name="One" type="asnx:BOOLEAN"/>
<field name="two" literalValue="99"/>
<field name="Three">
<valueSet>
<union>
<literalValue>1</literalValue>
<literalValue>2</literalValue>
</union>
</valueSet>
</field>
<field name="four" object="tns:myObject"/>
<field name="Five">
<objectSet>
<object ref="tns:myObject"/>
</objectSet>
</field>
</object>
</namedObject>
10.3. ObjectFromObject Translation
The translation of an ObjectFromObject is an element item with the
[local name] "object". An element item with the [local name]
"annotation" MAY be added to the [children] of the <object> element
item. An element item with the [local name] "fromObjects" SHALL be
appended to the [children] of the <object> element item.
The translation of the ReferencedObjects instance in the
ObjectFromObject SHALL be added to the [children] or [attributes] of
the <fromObjects> element item.
The translation of the FieldName in the ObjectFromObject SHALL be
added to the [children] or [attributes] of the <fromObjects> element
item.
11. Translation of Object Sets
If an ObjectSet matches the form "{ DefinedObjectSet }" (i.e., a
DefinedObjectSet in an ObjectSetElements instance in an Elements
instance in a lone IntersectionElements instance in a lone
Intersections instance in a Unions instance in an ElementSetSpec in a
RootElementSetSpec in an ObjectSetSpec without an
AdditionalElementSetSpec), then the translator MAY use the
translation of the DefinedObjectSet as the translation of the
ObjectSet; otherwise, the translation of an ObjectSet is an element
item with the [local name] "objectSet". An element item with the
[local name] "annotation" MAY be added to the [children] of the
<objectSet> element item. The translation of the ObjectSetSpec in
the ObjectSet SHALL be appended to the [children] of the <objectSet>
element item.
Aside: An ObjectSet that is directly a DefinedObjectSet is a
notational capability that does not exist in ASN.1, but is allowed
in ASN.X to avoid excessive nesting of <objectSet> element items
in the expansion of parameterized definitions.
If an ObjectSetSpec contains only a RootElementSetSpec, then the
translation of the ObjectSetSpec is the translation of the
ElementSetSpec in the RootElementSetSpec.
If an ObjectSetSpec contains a RootElementSetSpec and an ellipsis
("..."), then the translation of the ObjectSetSpec is the translation
of the ElementSetSpec in the RootElementSetSpec followed by an
element item with the [local name] "extension". If an
AdditionalElementSetSpec is present, then the translation of the
ElementSetSpec in the AdditionalElementSetSpec SHALL be added to the
[children] of the <extension> element item.
If an ObjectSetSpec does not contain a RootElementSetSpec, then the
translation of the ObjectSetSpec is an element item with the
[local name] "extension". If an AdditionalElementSetSpec is present,
then the translation of the ElementSetSpec in the
AdditionalElementSetSpec SHALL be added to the [children] of the
<extension> element item.
Nested within the ElementSetSpec will be one or more
ObjectSetElements instances.
11.1. DefinedObjectSet Translation
If a DefinedObjectSet is an objectsetreference (not a DummyReference)
or an ExternalObjectSetReference, then the translation of the
DefinedObjectSet is either the attribute form translation of an
object set reference, or the element form translation of an object
set reference.
The attribute form translation of an object set reference is an
attribute item with the [local name] "objectSet". The
[normalized value] of this attribute item is a qualified name for the
expanded name of the referenced object set definition (see
Section 5.1). The attribute form translation SHALL NOT be used if
this expanded name is not distinct with respect to the current module
and the modules referenced by its <import> element items (see
Section 5.1).
The element form translation of an object set reference is an element
item with the [local name] "objectSet". An element item with the
[local name] "annotation" MAY be added to the [children] of the
<objectSet> element item. An attribute item with the [local name]
"ref" SHALL be added to the [attributes] of the <objectSet> element
item. The [normalized value] of this attribute item is a qualified
name for the expanded name of the referenced object set definition.
If this expanded name is not distinct with respect to the current
module and the modules referenced by its <import> element items, then
an attribute item with the [local name] "context" SHALL be added to
the [attributes] of the <objectSet> element item; otherwise, if the
module containing the referenced object set definition has a schema
identity URI, then an attribute item with the [local name] "context"
MAY be added to the [attributes] of the <objectSet> element item.
The [normalized value] of this attribute item is the schema identity
URI of the module containing the referenced object set definition.
Aside: If a reference name is not distinct, then the module
containing the referenced definition must have a schema identity
URI (see Section 5.1).
The translation of the DefinedObjectSet is the same whether the
object definition is referenced by an objectsetreference or an
ExternalObjectSetReference.
Usually the translator is free to choose either the attribute form or
element form translation for an object set reference; however, in
some contexts the attribute form is explicitly disallowed.
If a DefinedObjectSet is a DummyReference, then the translation of
the DefinedObjectSet is the translation of the DummyReference (see
Section 13).
11.2. ObjectSetElements Translation
If an ObjectSetElements instance is an Object, then the translation
of the ObjectSetElements instance is the translation of the Object,
except that the attribute form of the DefinedObject translation SHALL
NOT be used if the Object is a DefinedObject.
If an ObjectSetElements instance is a DefinedObjectSet, then the
translation of the ObjectSetElements instance is the translation of
the DefinedObjectSet, except that the attribute form of the
DefinedObjectSet translation SHALL NOT be used.
If an ObjectSetElements instance is an ObjectSetFromObjects, then the
translation of the ObjectSetElements instance is the translation of
the ObjectSetFromObjects.
If an ObjectSetElements instance is a ParameterizedObjectSet, then
the translation of the ObjectSetElements instance is the translation
of the ParameterizedObjectSet (see Section 13).
Aside: The in-line expansion of a ParameterizedObjectSet results
in an ObjectSet. An ObjectSetElements instance that is an
ObjectSet is a notational capability that does not exist in ASN.1,
but is allowed in ASN.X to avoid the need to manufacture a
reference name for the expanded parameterized definition.
11.2.1. ObjectSetFromObjects Translation
The translation of an ObjectSetFromObjects instance is an element item with the [local name] "objectSet". An element item with the [local name] "annotation" MAY be added to the [children] of the <objectSet> element item. An element item with the [local name] "fromObjects" SHALL be appended to the [children] of the <objectSet> element item. The translation of the ReferencedObjects instance in the ObjectSetFromObjects SHALL be added to the [children] or [attributes] of the <fromObjects> element item. The translation of the FieldName in the ObjectSetFromObjects SHALL be added to the [children] or [attributes] of the <fromObjects> element item.12. Translation of Information From Objects
If a ReferencedObjects instance is a DefinedObject (not a DummyReference), then the translation of the ReferencedObjects instance is the translation of the DefinedObject. If a ReferencedObjects instance is a DefinedObjectSet (not a DummyReference), then the translation of the ReferencedObjects instance is the translation of the DefinedObjectSet. If a ReferencedObjects instance is a DummyReference, ParameterizedObject, or ParameterizedObjectSet, then the translation of the ReferencedObjects instance is the translation of that DummyReference, ParameterizedObject, or ParameterizedObjectSet (see Section 13). Aside: The in-line expansion of a ParameterizedObject or ParameterizedObjectSet results in an Object or ObjectSet, respectively. A ReferencedObjects instance that is an Object or ObjectSet is a notational capability that does not exist in ASN.1, but is allowed in ASN.X to avoid the need to manufacture a reference name for an expanded parameterized definition.13. Translation of Parameterized Definitions
The translation of an ASN.1 specification into ASN.X replaces any DummyReference [X.683] or reference to a parameterized definition [X.683] with the definition expanded in-line (except for a special case involving recursive parameterized types). For example, a ParameterizedObject is replaced by the Object on the right-hand side of the referenced ParameterizedObjectAssignment.
The definition that substitutes for a DummyReference or parameterized reference (e.g., the Object that substitutes for a ParameterizedObject) potentially comes from a different module from the reference. Expanding a DummyReference or parameterized reference in-line puts the substitute definition into the context of the module containing the reference, which could therefore alter the interpretation of the substitute definition. A type definition is potentially dependent on the TagDefault and ExtensionDefault of the module in which it appears, and may also be affected by encoding instructions in an XML Encoding Rules (XER) [X.693] encoding control section [X.693-1]. Other kinds of definitions are not dependent on the module context; however, type definitions can be nested within the other kinds of definitions, so a change of context can still be significant. Aside: Type definitions are not dependent on their module's RXER or Generic String Encoding Rules (GSER) [GSER] encoding control section [RXEREI][GSEREI] (as they are currently defined), so the presence of an encoding control section for RXER or GSER is not significant in a change of context. The remainder of this section describes how and when a change of context is indicated in the ASN.X translation of a DummyReference or parameterized reference. In any instance of use, the module containing the DummyReference or parameterized reference is the referencing module, and the module providing the substitute definition is the referenced module. The referenced and referencing modules may be the same module. In the case of a ParameterizedType, the substitute definition is the Type on the right-hand side of the referenced ParameterizedTypeAssignment. In the case of a ParameterizedValueSetType, the substitute definition is the constrained type on the right-hand side of the notional ParameterizedTypeAssignment equivalent to the referenced ParameterizedValueSetTypeAssignment (see Clause 15.8 of X.680 [X.680]). In the case of a ParameterizedValue, the substitute definition is the Value on the right-hand side of the referenced ParameterizedValueAssignment. In the case of a ParameterizedObjectClass, the substitute definition is the ObjectClass on the right-hand side of the referenced ParameterizedObjectClassAssignment.
In the case of a ParameterizedObject, the substitute definition is
the Object on the right-hand side of the referenced
ParameterizedObjectAssignment.
In the case of a ParameterizedObjectSet, the substitute definition is
the ObjectSet on the right-hand side of the referenced
ParameterizedObjectSetAssignment.
If the ActualParameter corresponding to a DummyReference is not a
ValueSet, then the substitute definition for that DummyReference is
the Type, Value, DefinedObjectClass, Object, or ObjectSet in the
ActualParameter.
If the ActualParameter corresponding to a DummyReference is a
ValueSet, then the substitute definition for that DummyReference is
the notional constrained type equivalent to the ValueSet; the
ElementSetSpecs of the ValueSet contributes to the constraint of the
constrained type, and the governor of the Parameter corresponding to
the ActualParameter is used as the parent type that is constrained.
Definition (interchangeable): The contexts of the referencing and
referenced modules are interchangeable with respect to interpreting
the substitute definition if:
(1) the referenced module is the referencing module and does not
contain an XER encoding control section, or
(2) the referenced module and referencing module have the same
TagDefault (where an absent TagDefault is taken to be equivalent
to "EXPLICIT TAGS"), the referenced module and referencing module
have the same ExtensionDefault, and neither module has an XER
encoding control section.
Aside: A module with an XER encoding control section is not
considered to have a context interchangeable with another module,
including itself, because the typereference by which a substitute
type definition is identified may appear in a TargetList in the
XER encoding control section of the referenced module, and because
the in-line expansion of a substitute definition may cause its
text to come within the scope of a TargetList in the XER encoding
control section of the referencing module that would not apply
otherwise.
Definition (recursively contained): A ParameterizedType is
recursively contained if its translation will be nested within the
translation (i.e., in-line expansion) of another ParameterizedType to
which it is equivalent. A ParameterizedValueSetType is recursively
contained if its translation will be nested within the translation of
another ParameterizedValueSetType to which it is equivalent.
Aside: ASN.1 does not permit the other kinds of parameterized
reference to be recursive.
The translation of a DummyReference, a ParameterizedType that is not
recursively contained, a ParameterizedValue, a
ParameterizedValueSetType that is not recursively contained, a
ParameterizedObjectClass, a ParameterizedObject, or a
ParameterizedObjectSet is either:
(a) the translation of the substitute definition, or
(b) an element item with the [local name] "type" if the substitute
definition is a Type, "value" if the substitute definition is a
Value, "class" if the substitute definition is an ObjectClass or
DefinedObjectClass, "object" if the substitute definition is an
Object, or "objectSet" if the substitute definition is an
ObjectSet. A fully expanded reference (described shortly) SHALL
be added to the [children] of the element item.
The translation in case (b) is always allowed and provides
information to identify the referenced module and the referenced
definition.
The translation in case (a) MAY be used instead if and only if the
contexts of the referencing and referenced modules are
interchangeable, or the contexts of the referencing and referenced
modules are not interchangeable, but the difference between them does
not affect how the substitute definition is interpreted.
Aside: There are many ways in which the substitute definition can
be unaffected by a difference between the contexts of the
referencing and referenced modules. One example would be where
the referencing and referenced modules differ only in their
TagDefault, but the substitute definition does not contain any
TaggedType notation.
Note that if the translation in case (a) is used, then the
referencing module is still the referencing module when considering a
nested in-line expansion. If the translation in case (b) is used,
then the referenced module becomes the referencing module when
considering a nested in-line expansion.
If case (a) is used for the translation of a DummyReference where the substitute definition is a Type, then an attribute form translation of the substitute definition SHALL NOT be used, and an attribute item with the [local name] "explicit" and [normalized value] "true" or "1" SHALL be added to the [attributes] of the <type> element item resulting from the translation of the substitute definition. Where the automatic tagging transformation applies [X.680], this attribute item indicates that explicit tagging applies to the type instead of the usual implicit tagging. If case (b) is used for the translation of a DummyReference where the substitute definition is a Type, then an attribute item with the [local name] "explicit" and [normalized value] "true" or "1" SHALL be added to the [attributes] of the <type> element item generated by case (b). A fully expanded reference is an element item with the [local name] "expanded". Except in the case of a DummyReference, the reference name is indicated by an attribute item with the [local name] "name" added to the [attributes] of the <expanded> element item. In the case of a ParameterizedType or ParameterizedValueSetType, the [normalized value] of this attribute item is the typereference of the ParameterizedType or ParameterizedValueSetType. In the case of a ParameterizedValue, the [normalized value] of this attribute item is the valuereference of the ParameterizedValue. In the case of a ParameterizedObjectClass, the [normalized value] of this attribute item is the objectclassreference of the ParameterizedObjectClass. In the case of a ParameterizedObject, the [normalized value] of this attribute item is the objectreference of the ParameterizedObject. In the case of a ParameterizedObjectSet, the [normalized value] of this attribute item is the objectsetreference of the ParameterizedObjectSet. The "name" attribute item MAY be omitted if: (1) the conditions permitting the use of the translation in case (a) are satisfied, or (2) the reference is not a typereference, or
(3) the reference is a typereference that does not appear in any
TargetList in an XER encoding control section of the referenced
module.
The "name" attribute SHALL NOT appear in the translation of a
DummyReference.
The referenced module is indicated by an element item with the
[local name] "module" added to the [children] of the <expanded>
element item. The <module> element item MAY be omitted if the
conditions permitting the use of the translation in case (a) are
satisfied, or if the referencing module is the referenced module.
When the <module> element item is present:
(1) An attribute item with the [local name] "name" SHOULD be added to
the [attributes] of the <module> element item. The
[normalized value] of this attribute item is the modulereference
in the ModuleIdentifier in the ModuleDefinition of the referenced
module.
(2) If the DefinitiveIdentifier in the ModuleIdentifier in the
ModuleDefinition of the referenced module is not empty, then an
attribute item with the [local name] "identifier" SHALL be added
to the [attributes] of the <module> element item. The
[normalized value] of this attribute item is the RXER character
data translation of the DefinitiveIdentifier.
(3) If the referenced module has a schema identity URI, then an
attribute item with the [local name] "schemaIdentity" SHALL be
added to the [attributes] of the <module> element item. The
[normalized value] of this attribute item is the schema identity
URI of the referenced module.
The [attributes] of the <module> element item MUST contain at least
one of the attribute items specified in cases (1), (2), and (3).
The translation of the substitute definition SHALL be added to the
[children] or [attributes] of the <expanded> element item.
Example
Consider these module definitions:
Templates
DEFINITIONS
AUTOMATIC TAGS ::=
BEGIN
CollectionOfThings { Thing } ::= SEQUENCE OF thing Thing
-- the Thing on the right-hand side of the assignment is
-- a DummyReference
END
ProtocolDefinitions
DEFINITIONS
AUTOMATIC TAGS ::=
BEGIN
IMPORTS
CollectionOfThings{}
FROM Templates
;
CollectionOfIntegers ::= CollectionOfThings { INTEGER }
-- the right-hand side of the assignment is
-- a ParameterizedType
END
Without using the translation in case (a), the translations of
these modules are:
<asnx:module name="Templates"/>
<asnx:module xmlns:asnx="urn:ietf:params:xml:ns:asnx"
name="ProtocolDefinitions">
<namedType name="CollectionOfIntegers">
<type>
<expanded name="CollectionOfThings">
<module name="Templates"/>
<type>
<sequenceOf>
<element name="thing">
<type>
<expanded>
<module name="ProtocolDefinitions"/>
<type ref="asnx:INTEGER"/>
</expanded>
</type>
</element>
</sequenceOf>
</type>
</expanded>
</type>
</namedType>
</asnx:module>
The translation of the Templates module is empty because the
module contains only a parameterized assignment.
Since the contexts of the Templates and ProtocolDefinitions
modules are interchangeable, a simpler translation of the
ProtocolDefinitions module is permitted:
<asnx:module xmlns:asnx="urn:ietf:params:xml:ns:asnx"
name="ProtocolDefinitions">
<namedType name="CollectionOfIntegers">
<type>
<sequenceOf>
<element name="thing">
<type ref="asnx:INTEGER" explicit="true"/>
</element>
</sequenceOf>
</type>
</namedType>
</asnx:module>
If a ParameterizedType or ParameterizedValueSetType is recursively
contained, then its translation is an element item with the
[local name] "type". An attribute item with the [local name]
"ancestor" SHALL be added to the [attributes] of the <type> element
item. The [normalized value] of this attribute item is the decimal
digit string representing the integer value of one plus the number of
intermediate enclosing <type> element items between the <type>
element items resulting from the translations of the two equivalent
instances of ParameterizedType or ParameterizedValueSetType. An
element item with the [local name] "annotation" MAY be added to the
[children] of the <type> element item.
A <type> element item with an ancestor attribute item is a reference
to an ancestor <type> element item. This form for a <type> element
item SHOULD NOT be used in original specifications written in ASN.X.
Aside: The form is only intended for the purpose of handling
recursive parameterized type definitions in an ASN.1 specification
being translated into ASN.X. Such definitions are
self-referencing, but have no obvious name. It is also not easy
to construct a suitable name from the surrounding context because
recursive parameterized types can be embedded in other constructs,
such as information objects, that are themselves unnamed.
Example
Consider these type definitions, assumed to be defined in a module
that does not have an XER encoding control section:
Tree { ValueType } ::= SEQUENCE {
value [0] ValueType,
left-subtree [1] Tree { ValueType } OPTIONAL,
right-subtree [2] Tree { ValueType } OPTIONAL
}
NumberTree ::= [APPLICATION 13] Tree { INTEGER }
The assignment for "Tree" is not directly translated because it is
a ParameterizedAssignment. The translation for the "NumberTree"
assignment, up to but not yet including the Type in the
TaggedType, is as follows:
<namedType name="NumberTree">
<type>
<tagged tagClass="application" number="13"/>
</type>
</namedType>
The Type in the TaggedType is a ParameterizedType. Since the
ParameterizedType is not recursively contained, the translation of
the ParameterizedType (using the translation in case (a) above) is
the translation of the Type on the right-hand side of the
referenced ParameterizedTypeAssignment, namely this type:
SEQUENCE {
value [0] ValueType,
left-subtree [1] Tree { ValueType } OPTIONAL,
right-subtree [2] Tree { ValueType } OPTIONAL
}
ValueType is a DummyReference. The translation of the actual
parameter substitutes for the DummyReference. In this case, the
actual parameter is the INTEGER type.
The translation for the SEQUENCE type, up to the first component,
is added to the <tagged> element:
<namedType name="NumberTree">
<type>
<tagged tagClass="application" number="13">
<type><!-- Tree { INTEGER } -->
<sequence>
<element name="value">
<type>
<tagged number="0">
<type ref="asnx:INTEGER"
explicit="true"/><!-- ValueType -->
</tagged>
</type>
</element>
</sequence>
</type>
</tagged>
</type>
</namedType>
The Type in the TaggedType for the second component is a
ParameterizedType. Since this ParameterizedType is recursively
contained, its translation is a <type> element with the ancestor
attribute. The value of the ancestor attribute is "2" because
there is one intermediate <type> element (for a TaggedType). Put
another way, the translations of the equivalent instances of
ParameterizedType are two <type> steps apart.
The translation of the third component of the SEQUENCE type
follows the same pattern as the second component. The completed
translation is as follows:
<namedType name="NumberTree">
<type>
<tagged tagClass="application" number="13">
<type><!-- Tree { INTEGER } -->
<sequence>
<element name="value">
<type>
<tagged number="0">
<type ref="asnx:INTEGER"
explicit="true"/><!-- ValueType -->
</tagged>
</type>
</element>
<optional>
<element name="left-subtree">
<type>
<tagged number="1">
<type ancestor="2"/><!-- Tree { ValueType } -->
</tagged>
</type>
</element>
</optional>
<optional>
<element name="right-subtree">
<type>
<tagged number="2">
<type ancestor="2"/><!-- Tree { ValueType } -->
</tagged>
</type>
</element>
</optional>
</sequence>
</type>
</tagged>
</type>
</namedType>
(page 93 continued on part 5)