Identity stays plural when necessary
A parcel can have multiple building records, and a building identifier can appear in conflicting contexts. Candidate and ambiguous states require explicit review.
Methodology
An evidence ledger—not an official determination.
The product joins source-linked assertions using deterministic identifiers and rules. It keeps uncertainty and source failure in the result instead of smoothing them away.
Assertions retain provenance
Unit, use, occupancy, and area values keep their source family, effective date where available, retrieval time, and evidence reference.
Relationships need evidence
A job can link to a permit without establishing completed work. A certificate link can be linked, partial, ambiguous, or not established.
Issue cards use literal rules
Accepted-source counts summarize Class B findings, Class C findings, and source-open backlog aging. They do not assess safety, condition, value, or future outcomes.
What PropSignal is—and is not
PropSignal organizes source-linked NYC public records for acquisition and ownership review. It is not owner-contact enrichment, valuation or underwriting software, a CRM, a compliance clearance, or a nationwide property database.
State vocabulary
Asserted
A source explicitly reports a value.
Missing
An expected field is absent from a record.
Not established
Available evidence does not prove the relationship or fact.
Conflicting
Two or more retained source assertions materially differ.
How sources are included
The property workspace checks a fixed inventory of fourteen public-evidence sources: five base property sources, two ACRIS tables, two HPD housing-operation sources, four DOB/HPD enforcement sources, and DOF rolling sales. A missing adapter remains visible as unavailable; it never disappears from the denominator.
Address and map sources support identity and exploration separately. Assessment-roll and stop-work records stay outside public property evidence until their source-specific reuse gates are resolved. Source records are not silently turned into incidents, legal effects, or proof that no other record exists.
Retrieval and source-effective time
PropSignal separates when evidence was retrieved from dates reported inside each source. Neither timestamp turns a source assertion into a legal or present-condition conclusion.
Four dates stay separate
Effective
When the source says the record or value applies, when supplied.
Published
When the source made a release or record available, when supplied.
Retrieved
When PropSignal fetched and preserved the accepted evidence.
Detected
When a deterministic comparison first found a retained evidence change.
How observed change is detected
- Seal a compatible accepted evidence release with source and retrieval lineage.
- Join stable property, assertion, event, and relationship identities without guessing.
- Compare normalized values and source state against the prior retained release.
- Label additions, corrections, retractions, recovery, and unresolved change literally.
- Keep reconstructed earlier history separate from evidence observed after collection began.
Method versions remain inspectable
Property evidence and dated packages retain the exact method identifiers used to build their facts, activity cards, history, and reports. A method change creates a new version; it does not silently reinterpret an earlier sealed package.
public_projection_v1@1.0- Source-linked public property assertions and evidence relationships.
hpd_public_activity_v1@1.0- Literal Class B, Class C, and source-open backlog activity rules.
EvidenceGuideRegistryV1@1.0- Reviewed static explanations of the evidence methods—not property results.
Apply the method to a real question
The evidence guides explain identity, disagreements, construction chronology, property activity, and observed history in plain language.
Browse the five evidence guides →