Property :: top - Position to top of collection

The function positions the property handle before the first instance in the collection according to the selected access key (current index). Thus, a subsequent call of next() or nextKey() will select the first instance in the collection. No instance is selected after calling the function.

When an instance had been selected in the property handle, it will be unselected (and stored when it was modified). For access paths the function can be used to initialize the access path. After opening an access path, the path has not been executed and is uninitialized until the next get() call. top() will initialize the path in advance.