## Data Formats and Validation

Date and time values must always be provided as **Unix timestamps (seconds)**.

For the data field type **Time** only timestamps representing the **first day of the Unix epoch date (00:00:00 UTC)** are accepted. Any time-of-day information beyond the day boundary is rejected.

Formatted date strings, locale-specific formats, and timezone annotations are not supported.

Incorrect field formats are one of the most common causes of errors when using the Listbuilding API. Always ensure that submitted values match the expected field type definitions.

Documentation:
[Data field types and Inputs](https://developers.klicktipp.com/guides/data-field-types)