Methods
Declaring unknowns
Distinguish not found, blocked by licence and not applicable, with a dated search boundary.
Problem
An empty field gives no account of whether anybody looked, whether a source was inaccessible, or whether the property makes sense for the subject. These cases lead to different next actions and different confidence in the record. A declared unknown is a scoped finding, not a claim that the value does not exist anywhere. Its usefulness depends on a visible search boundary, the time of the search, and a status that says why the field remains unfilled.
Steps
Define the question
Name the subject and property precisely, including jurisdiction, period and source class where those limits matter. Decide what would count as a positive answer before searching. A registry entry, a dated filing and a secondary article may have different authority for the same question. Without a defined question, "not found" can expand from "not in this registry" to "does not exist".
Record the search
List the sources or collections searched, their versions or access dates, the queries or identifiers used, and any filters that excluded material. Record search time separately from the date at which the requested value should apply. A future reviewer should be able to repeat the same bounded search and see which plausible sources were not searched.
Choose the status
Use "not found" when an accessible, relevant search returned no qualifying value; "blocked by licence" when material needed to decide cannot lawfully be read or retained; and "not applicable" when the property does not arise for that subject and date. State the grounds. A failed web request or an ambiguous result is not automatically evidence for one of these statuses.
Set a review trigger
Record what new evidence would change the status: a registry release, access to licensed material, a change in the subject's state, or a corrected identifier. Give the finding an observation date and preserve prior assessments when it changes. This makes an unknown inspectable and time-bound without pretending that repeated searches prove universal absence.
Checks
- The question and search boundary are explicit.
- The status explains absence, inaccessibility or irrelevance.
- Search date and review trigger are visible.
- A bounded search is not presented as universal proof.
Pitfalls
- Treating a blank cell as a finding.
- Using not found for inaccessible material.
- Using not applicable for a difficult search.
A worked example
A fictional analyst asks whether Halden Laboratory Services GmbH holds a manufacturing licence in a given country. The question is written down: a licence for named activities, in that country, valid on a stated date. The analyst searches the regulator's public register by name and by registration number, and the register returns no match.
The record does not say no licence. It says not found: the register at a given address was searched on a given date by two keys, and returned nothing. It also states what the search could not cover: the register lists only licences granted after a certain year, according to its own notes. The status carries a review trigger, namely the next published register release. When the register is updated and the licence appears, a new entry supersedes the old one, and the old one stays as the finding of its date.
Variations and edge cases
Conflict is not unknown. Where two sources give different answers, the right entry is a conflict with both candidates, not an unknown. Partial knowledge is not unknown either: a date known to the month is recorded at that precision. A failed request is not a finding. If the register was down, the status is that the search could not be completed, with the attempt noted, and the question stays open.
Not applicable needs its own care. It is a claim that the property does not arise for this subject, and it needs the rule that excludes it. A licence is not applicable to a company that does not carry out the licensed activity, and that fact has to be shown. Difficulty finding a value does not make a property inapplicable.
How readers use the status
Each status leads to an action. Not found invites a wider search or a different source. Blocked invites a request for access, or an authorized colleague to read the material. Not applicable ends the inquiry unless the subject changes. A blank leads to none of these, because no one knows which applies. In decision records, the declared status also protects the decision-maker: it shows that the gap was seen and weighed, not overlooked.
Statuses should be few and defined in writing, with examples. Reviewers should be able to reject an entry whose basis is missing, such as a not found with no search described. The same vocabulary appears in system outputs, in reports and in evaluation sets, so that a unknown means the same thing everywhere it is read.
References
Found an error on this page? See corrections for what counts as one, how to report it and the dated log.
Enquiry
Test this method on one entity.
Name an entity where "Declaring unknowns" would be checked in practice, with its sources and its readers. We reply with what a first record would cover and what it would need from you.
Or write to [email protected] in your own words.