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

# Data notes

> Known quirks in the source data and how to handle them.

Records are returned as publishers wrote them. These are the quirks worth knowing.

## Dates

* **Epoch milliseconds.** Some Virginia sources store dates as numbers of milliseconds since 1970, for example `1696118400000`. Convert before displaying.
* **Placeholder dates.** D.C. sales use `1900-01-01` when the date is unknown. Treat it as missing.
* **Last sale in `summary`.** The latest sale is chosen by comparing dates as text, so with the formats above `last_sale_price` and `last_sale_date` can come from an older sale. When the sale matters, check `alternatives` or read the sale `records`.

## Coverage gaps

* **Maryland** has no bedroom or bathroom counts.
* **Entity types differ by state.** Maryland has no parcels or units; Virginia has no tax accounts or units. See [Entities by state](/concepts/entities#entities-by-state).

## Duplicates

* **Arlington tax payments** appear twice: once from the county's bulk file and once from its API. Deduplicate on the payment fields when you total them.

## Catalog

* `catalog` with a county code returns the whole state's sources.
* Field statistics (`fill`, `example`) come from a 2,000-record sample.

## History

Each source has been published once so far, so [`history`](/api-reference/property-data/get-record-history) returns one version per record. Versions and removals appear as sources are refreshed.


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