====== multiLevelDown() ======

''void **multiLevelDown**(string //QuestionnaireIdentifier//, [mixed //Data//])''

The function ''multiLevelDown()'' starts the questionnaire with the identifier //questionnaireID// and passes any specified //data// to the child questionnaire.

**Note:** The ''multiLevelDown()'' command terminates the execution of the current PHP code and questionnaire page and jumps directly to the child questionnaire.

When the participant finishes the subordinate questionnaire (reaching the last page or using ''[[:en:create:functions:multilevelreturn]]''), he returns to the main questionnaire in which ''multiLevelDown()'' was used.

  * //questionnaireIdentifier//\\ Identifier of the questionnaire to be called.
  * //Data//\\ Data which should optionally be passed to the child questionnaire, and can be retrieved there using ''[[:en:create:functions:multileveldata]]''.

The use of this function is described in chapter [[:en:create:multilevel]] -> [[:en:create:multilevel#real_multi-level_design|real multilevel design]].


===== Assignment =====

By ''multiLevelDown()'' another case is created in the data set, in which the data from the subordinate questionnaire are stored.

The case number (CASE) of the parent case is noted in all subordinate cases of an interview in the variable REF. For example, if within one interview of the questionnaire "main" three subordinate cases of the questionnaire "sub" are created, the data structure could look like this:

^CASE^QUESTNNR^REF^Description^
|      1|     main|       |Participant A (parent questionnaire)       |
|      2|      sub|      1|Participant A (subordinate questionnaire 1)|
|      5|      sub|      1|Participant A (subordinate questionnaire 2)|
|      7|      sub|      1|Participant A (subordinate questionnaire 3)|

The cases are not necessarily directly below each other in the data set. If other interviews start between the creation of the subordinate questionnaires, they will stand between the cases, for example:

^CASE^QUESTNNR^REF^Description^
|      1|     main|       |Participant A (parent questionnaire)       |
|      2|      sub|      1|Participant A (subordinate questionnaire 1)|
|      3|     main|       |Participant B (superordinate questionnaire)|
|      4|     main|       |Participant C (superordinate questionnaire)|
|      5|      sub|      1|Participant A (subordinate questionnaire 2)|
|      6|      sub|      3|Participant B (subordinate questionnaire 1)|
|      7|      sub|      1|Participant A (subordinate questionnaire 3)|