# Internet Archive ARC file metadata XML Schema

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XML Instance Representation:
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Schema Component Representation:
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## Table of Contents

- Schema Document Properties
- Global Declarations
  - Element: arcmetadata
  - Element: hostname
  - Element: http-header-from
  - Element: http-header-user-agent
  - Element: ip
  - Element: operator
  - Element: robots
  - Element: software

- Legend

- Glossary

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## Schema Document Properties

Target Namespace | http://archive.org/arc/1.0/
Element and Attribute Namespaces | Global element and attribute declarations belong to this schema's target namespace. By default, local element declarations belong to this schema's target namespace. By default, local attribute declarations have no namespace.
Schema Composition | This schema imports schema(s) from the following namespace(s): http://www.w3.org/XML/1998/namespace (at http://www.w3.org/2001/03/xml.xsd) http://purl.org/dc/elements/1.1/ (at http://dublincore.org/schemas/xmls/qdc/2003/04/02/dc.xsd) http://purl.org/dc/terms/ (at http://dublincore.org/schemas/xmls/qdc/2003/04/02/dcterms.xsd)
Documentation | Internet Archive ARC file Dublin Core element refinements. XML Schema for http://archive.org/arc/1.0/ namespace. This schema adds Dublin Core element refinements for Internet Archive ARC file metadata. It also adds new elements that subclass the 'dc:any' type and the 'dc:metadata' element container. $Id$

### Declared Namespaces

Prefix | Namespace
--- | ---
Default namespace | http://archive.org/arc/1.0/
xml | http://www.w3.org/XML/1998/namespace
arc | http://archive.org/arc/1.0/
xs | http://www.w3.org/2001/XMLSchema
dc | http://purl.org/dc/elements/1.1/
dcterms | http://purl.org/dc/terms/

Schema Component Representation
<xs:schema targetNamespace="http://archive.org/arc/1.0/" elementFormDefault="qualified" attributeFormDefault="unqualified"> <xs:import namespace="http://www.w3.org/XML/1998/namespace" schemaLocation="http://www.w3.org/2001/03/xml.xsd"/> <xs:import namespace="http://purl.org/dc/elements/1.1/" schemaLocation="http://dublincore.org/schemas/xmls/qdc/2003/04/02/dc.xsd"/> <xs:import namespace="http://purl.org/dc/terms/" schemaLocation="http://dublincore.org/schemas/xmls/qdc/2003/04/02/dcterms.xsd"/> ... </xs:schema>

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## Global Declarations

### Element: arcmetadata

Name | arcmetadata
Type | dcterms:elementOrRefinementContainer
Nillable | no
Abstract | no
Documentation | Root container for ARC metadata. Can hold any 'dc:any' element. (All ARC elements are subclasses of the 'dc:any' type).

XML Instance Representation
<arcmetadata> dcterms:elementOrRefinementContainer </arcmetadata>

Schema Component Representation
<xs:element name="arcmetadata" type=" dcterms:elementOrRefinementContainer "/>

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### Element: hostname

This element can be used wherever the following element is referenced: dc:creator

Name | hostname
Type | anyType
Nillable | no
Abstract | no
Documentation | Element-refinement for 'dc:creator'. The hostname of the machine that created this resource. Example 'debord.archive.org'.

XML Instance Representation
<hostname> ... </hostname>

Schema Component Representation
<xs:element name="hostname" substitutionGroup="dc:creator"/>

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### Element: http-header-from

This element can be used wherever the following element is referenced: dc:any

Name | http-header-from
Type | anyType
Nillable | no
Abstract | no
Documentation | The HTTP 'From' header sent by the crawler along with each request. Example: 'webmaster@localhost.localdomain'. Note that this value will be removed from metadata when ARC files record the request sent (Currently the response only is recorded in ARCs).

XML Instance Representation
<http-header-from> ... </http-header-from>

Schema Component Representation
<xs:element name="http-header-from" substitutionGroup="dc:any"/>

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### Element: http-header-user-agent

This element can be used wherever the following element is referenced: dc:any

Name | http-header-user-agent
Type | anyType
Nillable | no
Abstract | no
Documentation | The HTTP 'user-agent' header sent by the crawler along with each request. Example: 'os-heritrix/0.7.0 (+http://crawler.archive.org)'. Note that this value will be removed from metadata when ARC files record the request sent (Currently the response only is recorded in ARCs).

XML Instance Representation
<http-header-user-agent> ... </http-header-user-agent>

Schema Component Representation
<xs:element name="http-header-user-agent" substitutionGroup="dc:any"/>

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### Element: ip

This element can be used wherever the following element is referenced: dc:creator

Name | ip
Type | anyType
Nillable | no
Abstract | no
Documentation | Element-refinement for 'dc:creator'. The IP address of the machine that created this resource. Example '123.1.2.3'.

XML Instance Representation
<ip> ... </ip>

Schema Component Representation
<xs:element name="ip" substitutionGroup="dc:creator"/>

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### Element: operator

This element can be used wherever the following element is referenced: dc:creator

Name | operator
Type | anyType
Nillable | no
Abstract | no
Documentation | Element-refinement for 'dc:creator'. Contact name and information for the operator who created this resource. Example: 'stack at archive dot org'.

XML Instance Representation
<operator> ... </operator>

Schema Component Representation
<xs:element name="operator" substitutionGroup="dc:creator"/>

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### Element: robots

This element can be used wherever the following element is referenced: dc:coverage

Name | robots
Type | anyType
Nillable | no
Abstract | no
Documentation | Element-refinement for 'dc:coverage'. The robots policy followed by the crawler harvesting this resource. Example: 'classic'.

XML Instance Representation
<robots> ... </robots>

Schema Component Representation
<xs:element name="robots" substitutionGroup="dc:coverage"/>

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### Element: software

This element can be used wherever the following element is referenced: dc:creator

Name | software
Type | anyType
Nillable | no
Abstract | no
Documentation | Element-refinement for 'dc:creator'. The software and software version used creating this resource. Example: 'heritrix 0.7.1 http://crawler.archive.org'.

XML Instance Representation
<software> ... </software>

Schema Component Representation
<xs:element name="software" substitutionGroup="dc:creator"/>

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## Legend

Complex Type: | AusAddress
Schema Component Type | Schema Component Name

Super-types: | Address < AusAddress (by extension)
Sub-types: | QLDAddress (by restriction)

If this schema component is a type definition, its type hierarchy is shown in a gray-bordered box.

Name | AusAddress
Abstract | no

The table above displays the properties of this schema component.

XML Instance Representation
<... country="Australia" > <unitNo> string </unitNo> [0..1] <houseNo> string </houseNo> [1] <street> string </street> [1] Start Choice [1] <city> string </city> [1] <town> string </town> [1] End Choice <state> AusStates </state> [1] <postcode> string <<pattern = [1-9][0-9]{3}>> </postcode> [1] ? </...>

The XML Instance Representation table above shows the schema component's content as an XML instance.

- The minimum and maximum occurrence of elements and attributes are provided in square brackets, e.g. [0..1].
- Model group information are shown in gray, e.g. Start Choice ... End Choice.
- For type derivations, the elements and attributes that have been added to or changed from the base type's content are shown in bold.
- If an element/attribute has a fixed value, the fixed value is shown in green, e.g. country="Australia".
- Otherwise, the type of the element/attribute is displayed.
  - If the element/attribute's type is in the schema, a link is provided to it.
  - For local simple type definitions, the constraints are displayed in angle brackets, e.g. <<pattern = [1-9][0-9]{3}>>.
- If a local element/attribute has documentation, it will be displayed in a window that pops up when the question mark inside the attribute or next to the element is clicked, e.g. <postcode>.

Schema Component Representation
<complexType name="AusAddress"> <complexContent> <extension base=" Address "> <sequence> <element name="state" type=" AusStates "/> <element name="postcode"> <simpleType> <restriction base=" string "> <pattern value="[1-9][0-9]{3}"/> </restriction> </simpleType> </element> </sequence> <attribute name="country" type=" string " fixed="Australia"/> </extension> </complexContent> </complexType>

The Schema Component Representation table above displays the underlying XML representation of the schema component. (Annotations are not shown.)
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## Glossary

Abstract (Applies to complex type definitions and element declarations). An abstract element or complex type cannot used to validate an element instance. If there is a reference to an abstract element, only element declarations that can substitute the abstract element can be used to validate the instance. For references to abstract type definitions, only derived types can be used.

All Model Group Child elements can be provided in any order in instances. See: http://www.w3.org/TR/xmlschema-1/#element-all.

Choice Model Group Only one from the list of child elements and model groups can be provided in instances. See: http://www.w3.org/TR/xmlschema-1/#element-choice.

Collapse Whitespace Policy Replace tab, line feed, and carriage return characters with space character (Unicode character 32). Then, collapse contiguous sequences of space characters into single space character, and remove leading and trailing space characters.

Disallowed Substitutions (Applies to element declarations). If substitution is specified, then substitution group members cannot be used in place of the given element declaration to validate element instances. If derivation methods, e.g. extension, restriction, are specified, then the given element declaration will not validate element instances that have types derived from the element declaration's type using the specified derivation methods. Normally, element instances can override their declaration's type by specifying an `xsi:type` attribute.

Key Constraint Like Uniqueness Constraint, but additionally requires that the specified value(s) must be provided. See: http://www.w3.org/TR/xmlschema-1/#cIdentity-constraint_Definitions.

Key Reference Constraint Ensures that the specified value(s) must match value(s) from a Key Constraint or Uniqueness Constraint. See: http://www.w3.org/TR/xmlschema-1/#cIdentity-constraint_Definitions.

Model Group Groups together element content, specifying the order in which the element content can occur and the number of times the group of element content may be repeated. See: http://www.w3.org/TR/xmlschema-1/#Model_Groups.

Nillable (Applies to element declarations). If an element declaration is nillable, instances can use the `xsi:nil` attribute. The `xsi:nil` attribute is the boolean attribute, nil, from the http://www.w3.org/2001/XMLSchema-instance namespace. If an element instance has an `xsi:nil` attribute set to true, it can be left empty, even though its element declaration may have required content.

Notation A notation is used to identify the format of a piece of data. Values of elements and attributes that are of type, NOTATION, must come from the names of declared notations. See: http://www.w3.org/TR/xmlschema-1/#cNotation_Declarations.

Preserve Whitespace Policy Preserve whitespaces exactly as they appear in instances.

Prohibited Derivations (Applies to type definitions). Derivation methods that cannot be used to create sub-types from a given type definition.

Prohibited Substitutions (Applies to complex type definitions). Prevents sub-types that have been derived using the specified derivation methods from validating element instances in place of the given type definition.

Replace Whitespace Policy Replace tab, line feed, and carriage return characters with space character (Unicode character 32).

Sequence Model Group Child elements and model groups must be provided in the specified order in instances. See: http://www.w3.org/TR/xmlschema-1/#element-sequence.

Substitution Group Elements that are members of a substitution group can be used wherever the head element of the substitution group is referenced.

Substitution Group Exclusions (Applies to element declarations). Prohibits element declarations from nominating themselves as being able to substitute a given element declaration, if they have types that are derived from the original element's type using the specified derivation methods.

Target Namespace The target namespace identifies the namespace that components in this schema belongs to. If no target namespace is provided, then the schema components do not belong to any namespace.

Uniqueness Constraint Ensures uniqueness of an element/attribute value, or a combination of values, within a specified scope. See: http://www.w3.org/TR/xmlschema-1/#cIdentity-constraint_Definitions.

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