Translations:ExpressionScript - Presentation/108/en
From LimeSurvey Manual
In order to properly build the JavaScript for a page, EM needs to know which variables are set on the page, and what their JavaScript ID is (e.g., for document.getElementById(x)). It must also know which variables are set on other pages (so that it can ensure that the needed <input type='hidden' value='x'> fields are present and populated).