=== doc_core_api ===

Ralf Hettinger, 08.08.2009: ''[TYPO3-core] RFC: Feature #7531: TCA displayCond - allow ANDed and/or ORed rulesets'':
<pre>
 Chapter: 4.2. $TCA array reference => ['columns'][fieldname] section , Key displayCond
 
 change Datatype to: string or array
 
 change Description:
 << Contains a condition rule for whether to display the field or not.
 >> Contains one rule or a ruleset of multiple rules for whether to display the field or not. One rule can be set as a string, multiple rules may be set as an array (see below).
 
 change Description (addition at the end):
 For passing multiple displayCond rules as a ruleset, they have to be grouped into an array with the keys AND and/or OR. Those keys are pointing to arrays, which contain elements being either strings (a single displayCond rule as described above) or arrays (again with keys being AND and/or OR and then containing another ruleset).
 Example: 
 The following ruleset is true, if (my_field1 && my_field2!=3 && (my_field3 || my_field4 || my_field5 && my_field6) || my_field7 || my_field8) :
 [code]
 'displayCond' => array (
   'AND' => array (
     'FIELD:my_field1:REQ:true',
     'FIELD:my_field2:!=:3',
     'OR' => array (
       'FIELD:my_field3:REQ:true',
       'FIELD:my_field4:REQ:true',
       'AND' => array(
         'FIELD:my_field5:REQ:true',
         'FIELD:my_field6:REQ:true',
       )
     )
   ),
   'OR' => array (
     'FIELD:my_field7:REQ:true',
     'FIELD:my_field8:REQ:true',
   )
 ),
 [/code]
 </pre>