Placeholder text for the field. This can be a simple string or a reference to a value in the current record or another one. With a syntax like __row|field the placeholder will take the value of the given field from the current record.

This can be recursive to follow a longer path in a table record chain. If the designated field is a relation to another table (is of type select, group or inline), the related record will be loaded and the placeholder searched within it.

Example from the “sys_file_reference” table:

'title' => [
   'label' => 'LLL:EXT:lang/locallang_tca.xlf:sys_file_reference.title',
   'config' => [
      'type' => 'input',
      'size' => 20,
      'eval' => 'null',
      'placeholder' => '__row|uid_local|metadata|title',
      'mode' => 'useOrOverridePlaceholder'

In the above placeholder syntax, uid_local points to the related “sys_file” record and metadata points to the “sys_file_metadata” of the related “sys_file” record. From there we take the content of the title field as placeholder value.