1. Purpose

This Technical Note establishes Bureau procedure for assessing Digital Objects whose historical function, meaning or presentation depends upon resources maintained at separate network locations.

Such dependencies may include hyperlinks, embedded media, remotely hosted files, external services, application interfaces, scripts, images, frames, directories or other independently maintained resources.

A Digital Object may remain publicly accessible while these dependencies disappear or change.

The continued accessibility of the primary object shall therefore not be treated as sufficient evidence that the complete historical experience remains preserved.

2. Scope

This procedure applies where a Digital Object:

• contains links to external resources;
• incorporates material hosted outside the primary network location;
• relies upon independently operated services;
• functions as a directory, portal, index or collection of network references;
• derives historical meaning from the identity of linked destinations;
• or otherwise depends upon resources outside the Bureau-defined boundary of the primary object.

The procedure may be applied to surviving original resources, archival representations and reconstructed environments where network dependencies form part of the preservation assessment.

3. Network-Dependent Digital Objects

For Bureau purposes, a network-dependent Digital Object is a Digital Object whose historical presentation, operation or meaning depends materially upon one or more independently maintained network resources.

The dependency need not be technical in the narrow sense.

A page may remain technically functional while losing substantial historical meaning because the destinations to which it refers have disappeared or changed.

Examples include:

• Web directories;
• curated link collections;
• Web rings;
• portal pages;
• weblogs containing significant external references;
• advertising pages containing linked graphical areas;
• embedded media hosted by third parties;
• remotely loaded scripts or application components;
• and interfaces dependent upon external network services.

The extent of dependency shall be determined from the historical function of the object rather than from the number of external references alone.

4. Primary Object and Dependent Resources

Assessment shall distinguish between the primary object and its dependent resources.

The primary object is the resource or bounded collection of resources recorded by the Bureau as the Digital Object under examination.

A dependent resource is an external resource necessary to reproduce, understand or interact with some part of the object’s historical state.

This distinction is analytical rather than absolute.

A resource treated as dependent in one catalogue record may itself be recorded as a separate Digital Object elsewhere in the Forgotten Web Exchange.

5. Dimensions of Preservation

Network-dependent Digital Objects shall not be assessed using accessibility alone.

Where applicable, the Bureau should examine at least four distinct dimensions.

5.1 Primary-Object Accessibility

Whether the primary Digital Object remains available at a verified network location or through a preserved representation.

5.2 Visual Integrity

Whether the visible presentation of the object remains substantially consistent with the historical state under examination.

5.3 Functional Integrity

Whether interactions necessary to the historical operation of the object continue to function as intended.

5.4 Dependent Network Context

Whether external resources upon which the object historically depended remain available and continue to represent substantially the same resources.

A finding in one dimension shall not automatically determine a finding in another.

6. Link Availability

A hyperlink may be considered available when an examination successfully obtains a response from its destination or from an expected redirect chain.

Availability is a technical observation.

It does not establish historical continuity.

A responding network location may contain:

• the historical destination;
• a modified continuation of that destination;
• a replacement resource;
• an unrelated resource;
• a domain-parking page;
• a resale page;
• or another resource occupying the same network location.

The Bureau shall therefore distinguish link availability from destination identity.

7. Link Decay

For purposes of preservation assessment, link decay is the loss or degradation of a network relationship recorded within a Digital Object.

Link decay may include:

• a destination becoming unavailable;
• DNS failure;
• persistent server failure;
• removal of the referenced path;
• redirection to an unrelated resource;
• domain expiration or reassignment;
• replacement of the historical destination;
• or loss of the relationship between the link and the object it historically identified.

Link decay is therefore broader than the occurrence of an HTTP error.

A link returning a successful response may nevertheless be historically degraded.

8. Destination Continuity

Where the identity of a linked destination materially affects preservation, the Bureau should assess whether the currently accessible destination represents the resource historically referenced.

The procedures established in TN-000002 shall be applied where a domain or network location appears to have been redirected, reassigned or repurposed.

Where necessary, TN-000003 may be applied to determine whether an accessible resource represents an original, restored, mirrored, reconstructed or recreated instance.

A successful response shall not by itself be recorded as evidence of destination continuity.

9. Redirects

Redirects shall be examined as part of the network relationship rather than automatically treated as successful preservation.

A redirect may represent legitimate migration of the historical destination.

It may also represent:

• organisational restructuring;
• domain consolidation;
• replacement content;
• domain parking;
• commercial resale;
• tracking infrastructure;
• or reassignment to an unrelated operator.

Where the redirect destination cannot be connected to the historical resource with sufficient evidence, continuity shall be recorded as unresolved.

10. Embedded and Remote Resources

Network dependency is not limited to hyperlinks selected by a user.

A Digital Object may automatically retrieve external components required for its presentation or operation.

Examples include:

• images;
• stylesheets;
• scripts;
• fonts;
• frames;
• multimedia;
• advertisements;
• application data;
• authentication services;
• and remote interfaces.

Loss of such resources may alter the object even when the primary document remains available.

The Bureau should record whether dependency loss affects appearance, functionality, interpretation or all three.

11. Assessment of Large Link Sets

Some Digital Objects contain hundreds or thousands of external references.

Where comprehensive examination is practical, the Bureau may test the complete set.

Where comprehensive examination is not practical, a documented sample may be used.

Any sampled examination shall record:

• the sampling method;
• the number of references examined;
• the date of examination;
• the criteria used to determine availability;
• the criteria used to determine continuity;
• and known limitations of the sample.

Results obtained from a sample shall not be presented as measurements of the complete object unless the method supports such inference.

12. Automated Examination

Automated tools may be used to identify network responses, redirects and apparent failures.

Automated results shall be treated as technical observations requiring interpretation.

Automated examination may be affected by:

• rate limiting;
• bot protection;
• temporary service failure;
• geographic restrictions;
• authentication requirements;
• certificate errors;
• client compatibility;
• and server behaviour specific to automated requests.

An automated failure shall therefore not automatically be recorded as permanent loss.

Likewise, an HTTP success response shall not automatically be recorded as historical continuity.

13. Temporal Qualification

Link condition is time-dependent.

Every formal link assessment shall record the date on which observations were made.

Measurements from previous research may be retained as historical evidence, but shall not be presented as current measurements without renewed verification.

Where multiple dated assessments exist, the Bureau may use them to document change in the dependent network environment over time.

This distinction is particularly important when external studies are used as evidence.

14. Archival Representations of Dependent Resources

Where a historical destination is no longer available, archival representations may provide evidence of the relationship formerly expressed by the Digital Object.

The Bureau should record:

• the historical network location;
• the date or approximate period of the reference;
• available archival captures;
• the relationship between the primary object and the archived destination;
• and limitations affecting the archival representation.

An archived destination does not restore the original live network relationship.

It may nevertheless preserve evidence necessary to understand that relationship.

15. Assessment Outcomes

Where network dependency materially affects the preservation condition of a Digital Object, the Bureau may record one or more of the following findings.

Dependent Context Intact

Material dependencies remain available and retain sufficient continuity with their documented historical state.

Dependent Context Partially Degraded

Some material dependencies are unavailable, altered or unresolved, but the object retains substantial historical function and meaning.

Dependent Context Substantially Degraded

Loss or alteration of dependencies materially limits reconstruction of the historical function or network context.

Dependent Context Lost

The relevant dependent environment can no longer be operationally reproduced from publicly accessible resources.

Dependent Context Unresolved

Available evidence is insufficient to determine the condition or continuity of material dependencies.

These findings supplement rather than replace the operational and preservation status of the primary Digital Object.

16. Overall Preservation Assessment

The Bureau shall avoid reducing a network-dependent object to a single binary finding of preserved or lost.

A resource may simultaneously exhibit:

• confirmed primary accessibility;
• strong visual integrity;
• degraded functional integrity;
• and substantial loss of dependent network context.

The preservation record should retain these distinctions where they materially affect interpretation of the object.

A surviving page shall not be described as completely preserved merely because its primary URL continues to respond.

17. Catalogue Treatment

The Forgotten Web Exchange record should describe dependency loss where it is material to the historical identity or operation of the object.

The primary historical network location shall remain recorded independently from the status of linked destinations.

Where a dependent resource is itself historically significant, it may be entered as a separate Digital Object and related to the originating record.

Catalogue terminology should distinguish:

• accessibility of the primary object;
• integrity of the primary object;
• availability of dependencies;
• and continuity of dependent resources.

18. Evidence and Attribution

Claims concerning link condition shall identify the date and method of examination.

Where findings are derived from external research, the source and date of that research shall be identified.

Historical measurements shall not be silently converted into contemporary measurements.

Where destination identity cannot be established, the Bureau shall record the uncertainty rather than infer continuity from technical availability.

Source treatment shall otherwise follow PM-000002.

19. Relationship to the Million Dollar Homepage Examination

FR-000003 documented the preservation condition of the Million Dollar Homepage, FWX-000001.

That examination found strong persistence of the primary visual artifact while also documenting substantial historical degradation of the network environment represented by its outbound links.

The case demonstrated that accessibility of a primary Web resource may substantially outlast the external resources upon which part of its historical function depended.

The present Technical Note formalises the assessment principles identified during that examination.

The Million Dollar Homepage should therefore be regarded as an illustrative case rather than the sole intended application of this procedure.

20. Relationship to Existing Procedure

This Technical Note supplements TN-000001 by extending verification beyond primary-resource accessibility.

It supplements TN-000002 where dependent network locations have been redirected, reassigned or repurposed.

It supplements TN-000003 where examination requires determination of whether a currently accessible dependent resource represents an original, restored, mirrored, reconstructed or recreated resource.

It shall be applied together with PM-000002 where external evidence, archival captures or previous measurements are used to support an assessment.

21. Preservation Principle

The Bureau adopts the following principle for network-dependent Digital Objects:

Preservation of a networked Digital Object requires consideration of both the object and the relationships through which it operated.

The loss of a dependent resource does not necessarily constitute loss of the primary object.

Conversely, survival of the primary object does not establish preservation of its complete historical function.

These conditions shall be documented separately.

22. Maintenance of this Procedure

This procedure shall be reviewed as Bureau experience with network-dependent Digital Objects develops.

Future revision may establish additional guidance for automated link examination, dependency mapping, preservation sampling and longitudinal comparison of network relationships.

Material changes shall be issued through the Bureau’s established publication control procedure.

---

Dr. Evelyn Rothen
Chief Preservation Officer
Office of Digital Preservation
Bureau of Digital Antiquities
1 October 2026