How does the "Clear Field Value" post-function work on radio button and select fields?

[Rob Horan]

Will it just nullify the field value or will it reset the field back to a default value, if one has been set for the field?

[Nic Brough -Adaptavist-]

For system fields, it nulls them out in the database.  For custom fields, it removes the line for value in the database.

On the front end, both of these work the same - the field is empty, with no options selected.  It doesn't set them to default.