[horde] enum vs. multienum

[Liebe Markus (AE/BA-S) *]

Hi,

I created a form and put an enum field on it:

$this->addVariable('Add', 'iso_add', 'enum', true, false, 
                  'Name for additional environment to rsync to root from RS',
                  array(
                        $this->addEntries, 
                        true
                  ));

The form gets rendered and the sql driver stores the selected value in the db.

As this did not really fit my needs, I changed the field to a multienum:

$this->addVariable('Add', 'iso_add', 'multienum', true, false, 
                  'Name for additional environment to rsync to root from RS',
                  array(
                        $this->addEntries, 
                        count($this->addEntries)
                  ));

The form gets rendered, has the values in it, and I can select multiple entries, but at this point the data is not stored anymore in the db. 
I think that the multienum gives back another datatype than the enum-field, but I cannot find hints on how to use it properly. 
Is there any documentation available somewhere on how to use the multienum field?

Markus