> For the complete documentation index, see [llms.txt](https://docs.os.uk/os-apis/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.os.uk/os-apis/accessing-os-apis/os-features-api/technical-specification/empty-values.md).

# Empty values

The OS Features API only returns attributes that are populated with values.

Depending on your implementation or the software you use to access the API you may find inconsistencies in the way missing attributes are handled.

For example, QGIS 3.4 treats the value of a missing attribute of type integer on a feature as a `NULL` value in its data view, whereas a missing attribute of string type is treated as an empty string.


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