[TYPO3-english] TCA relations not by uid field

[Dmitry]

In my TCA I have relation n:1 SuperClass -> Code

'super_class' => [
'exclude' => true,
'label' => 'Super Class',
'config' => [
'type' => 'select',
'renderType' => 'selectSingle',
'foreign_table' => 'tx_classification_item',
'minitems' => 0,
'maxitems' => 1,
],
],

Field "super_class" related to field "uid". I need to set relation between "super_class" and "code" fields, not "uid" field. Can I do it?