> ## Documentation Index
> Fetch the complete documentation index at: https://docs.altss.com/llms.txt
> Use this file to discover all available pages before exploring further.

# Dates & freshness

> Publication, capture, observation and verification are different events.

## Role dates and validity

A person’s recorded employment start/end dates can describe that role’s history at the source’s precision. They are distinct from a capture, observation or verification timestamp.

Generic relationship valid\_from / valid\_to fields are not part of this public contract. A database history field or page modification date must not become a customer-visible validity claim.

## Date semantics

| Date           | Meaning                                           | When absent                                       |
| -------------- | ------------------------------------------------- | ------------------------------------------------- |
| publishedAt    | When the source was published                     | Unknown; do not substitute capture time           |
| capturedAt     | When that source was acquired                     | Unknown; not a verification date                  |
| observedAt     | When the fact or event was observed               | Unknown; preserve a date-only source as date-only |
| verifiedAt     | When the underlying fact was explicitly rechecked | Unknown; a record update is not verification      |
| dataMeasuredAt | When an aggregate population was measured         | Unknown; not each entity’s verification date      |
| lastModified   | When public page content changed                  | Not evidence that the underlying company changed  |

The descriptive evidence JSON uses published\_at, captured\_at, observed\_at and verified\_at for the same meanings. Every field does not have every date. Date-only evidence stays in its source note; never invent a timestamp.

## Provenance availability

Supporting source references and notes belong beside permitted facts in a bounded result. Subscription views do not expose a citation URL or every date for every field, including all commitments. Missing provenance cannot be repaired by treating record modification time as source publication or verification.

Public records carry source-specific dates where available. No population-wide measured refresh cadence or universal verification deadline is established here. Page modified, source captured, fact observed, entity verified and aggregate measured describe different events. Check the date attached to the relevant claim; a missing verification date means unknown. Stored source history does not establish a customer-facing historical-analysis interface.