TYPO3 v7 has reached its end-of-life November 30th, 2018 and is not maintained by the community anymore. Looking for a stable version? Use the version switch on the top left.
There is no further ELTS support. It is recommended that you upgrade your project and use a supported version of TYPO3.
Can be saved/updated through TCE but the value is not evaluated in any way and the field has no rendering in the TCEforms.
You can use this to send values directly to the database fields without any automatic evaluation. But still the update gets logged and the history/undo function will work with such values.
Since there is no rendering mode for this field type it is specifically fitted for direct API usage with the TCEmain class.