Metadata as Mediation

This post is part of a series that explores how metadata can be used as a site of resistance, refusal, and poetic subversion. From classification to linked data, the series investigates how cataloging practices can encode oppression, and how they can be reimagined to challenge dominant systems and speak from the margins. Check all the posts in this section's index.

The Space Between Vocabularies

Micro-thesauri, built at the scale of communities, labs, and collections, have already demonstrated that semantic autonomy is not only possible but necessary. Their granularity and accountability allow meaning to remain situated, contextual, and alive. But no vocabulary — however grounded — remains entirely within itself. Repositories ingest data from multiple sources. Archives must expose records to external discovery layers. Scientific infrastructures link datasets across continents. The question is therefore unavoidable: what happens when a small vocabulary meets a large one?

For most of the past century, the answer has been assimilation. Local vocabularies were treated as raw material for "integration," their distinctions sanded down to fit the broader schema. The result was universal interoperability at the cost of epistemic erasure. The mediation layer proposed here arises as a direct refusal of that model. Instead of forcing vocabularies upward, it constructs the connective space between them: an operational membrane designed to let meanings travel without demanding that they become identical.

The Architecture of Translation

Mediation is not a metaphysical gesture, it is an infrastructural one. In distributed systems, interoperability is achieved not by merging codebases but by establishing gateways, brokers, and protocols that translate between them while preserving their independence.

Metadata infrastructures require a similar shift. Instead of asking small vocabularies to align themselves with a dominant ontology, the mediation layer assumes responsibility for encounter. It performs translation at runtime, without altering the source vocabulary. This architectural inversion matters: semantic labor moves from the periphery to the middle. The connective tissue becomes the site of expertise, negotiation, and accountability.

Within this architecture, translation is no longer a silent operation performed behind the scenes. It becomes explicit, documented, and reversible. A mediation system acknowledges that every mapping is an interpretation, and that interpretations require provenance, justification, and periodic revision. The purpose of mediation is not to find the perfect equivalence but to make visible the conditions under which equivalence becomes possible and the limits beyond which it should not be attempted.

Governing the Act of Translation

If translation is an interpretive act, it demands governance. Not in the sense of centralized authority, but as a distributed practice that records how mappings are proposed, contested, stabilized, or withdrawn.

The first layer of this governance is the translation registry. Its task is deceptively simple: to store mappings among vocabularies. However, the registry's political function lies in its refusal to designate a single mapping as definitive. A concept may map differently depending on disciplinary perspective, community knowledge, or contextual use. A responsible mediation layer records these parallel assertions rather than collapsing them.

Alongside registries, mapping ontologies provide the semantics of translation. Conventional predicates — exact equivalence, hierarchical containment, associative connection — capture only a fraction of the relations that emerge when vocabularies reflect lifeworlds rather than taxonomies. Ritual, seasonal, embodied, or socially restricted knowledge cannot be reduced to static equivalence. Their mappings require expressions of conditionality, partiality, or refusal. A mediation layer must therefore support forms of correspondence that encode limits, fractures, and asymmetries, acknowledging that some concepts cannot and should not be rendered into another system's logic.

The Broker as Interface

Mediation becomes operational when these translations are enacted. This is the role of the broker: an intermediary system capable of ingesting heterogeneous vocabularies and applying the appropriate mapping logic without modifying the sources. The broker reads a micro-thesaurus in the terms of its own governance, preserves its structure, and produces a transformed representation suitable for a repository, aggregator, or discovery interface.

The broker's task is architectural humility. It does not correct vocabularies, absorb them, or enforce a hierarchy. Instead, it stages a reversible encounter. Meaning passes through the broker and emerges intelligible to another system without surrendering its original definition.

This logic already exists in partial form across scientific cyberinfrastructures. Biodiversity platforms process incoming datasets through configurable translation pipelines. Cultural-heritage aggregators perform ingestion via mapping rules that preserve local metadata while producing a common lens for discovery. These systems were not designed with epistemic plurality in mind, but their architecture demonstrates the feasibility of a mediation layer that treats translation as a configurable, visible process rather than a mandate.

Preserving Difference Across Systems

A mediation layer is ethical only if it maintains the integrity of the vocabularies it connects. This requires the ability to register not only successful mappings but gaps, conditions, and limits. Some terms resist translation because they encode relations or obligations that exist only within a specific community or ecological context. Others cannot be transferred without compromising the secrecy, seasonality, or embodied nature of the knowledge they represent.

The mediation layer must preserve these boundaries. It must allow for intentional silences, non-equivalences, and withheld mappings. In doing so, it acknowledges that interoperability is not an absolute good. It is a negotiated function whose scope depends on context, purpose, and consent. Maintaining difference, in this architectural sense, is not resistance to interoperability — it is its precondition. Systems interoperate responsibly only when they do not presume sameness.

Toward a Federated Semantic Ecology

When mediation becomes a core design principle, vocabularies stop behaving like nodes in a hierarchy and begin functioning as members of a federation. Each retains governance over its internal logic. Each evolves at its own rhythm. Each asserts the distinctions that matter to its users and communities. The mediation layer forms the connective mesh: a space where translations are documented, mappings are contested, and meanings are allowed to meet without erasing one another.

In this federated ecology, interoperability is not the enforcement of a common language but the cultivation of a shared architectural grammar. The system does not ask vocabularies to change themselves. It requires only that they make their boundaries legible, their terms accountable, and their relations negotiable. Mediation becomes the infrastructure that lets plurality remain intact while enabling communication at multiple scales.

Conclusion: The Politics of the Interstitial

Metadata often presents itself as a language of certainty, but its future depends on the infrastructures that operate in uncertainty — the places where translations falter, where equivalences break down, and where meanings rub against each other without fusing. Mediation is the architecture of that friction. It transforms the interstitial into the site of governance, responsibility, and philosophical clarity.

Neutrality between vocabularies is neither possible nor desirable. Translation always carries friction, and that friction is precisely where meaning retains its integrity. A mediation layer does not smooth those edges; it gives them structure. It creates channels through which worlds can meet without being collapsed into one another, and it treats the interstitial not as an empty corridor but as a governed space where boundaries, refusals, and correspondences remain visible. In that space, difference is not an obstacle to interoperability but the condition that makes it honest — a reminder that connection is strongest when it does not require erasure.