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+Custom elements can be configured to have user-defined properties, to behave in
+their own special way, to interact with other elements, to change their
+behaviour on certain conditions (by changing into other custom elements with
+different properties) or to trigger actions that influence the game.
+
+Each level has its own set of custom elements. To use the same custom elements
+within one level set, use the "copy and paste" functions or use "save as
+template" and "use template" to use the same custom elements from a single level
+template for all levels of a set.