void CMarkup::GotoChildElemIndex( int nIndex );

GotoChildElemIndex is only in CMarkup Developer and the free XML editor  FOAL C++ scripting.

GotoChildElemIndex sets the current child position to the element at the specified index. The element that contains it will automatically become the main position element. See ElemIndex Navigation for the full story on all the ElemIndex methods.

Element indexes can be retrieved with GetElemIndex, GetChildElemIndex and GetParentElemIndex. In addition to GotoChildElemIndex, there are GotoElemIndex and GotoParentElemIndex methods.

The ElemIndex functions provide access to the internal element indexing of CMarkup. Do not attempt to goto an index of an element that may have been deleted. Also, indexes are only valid during the course of the CMarkup object's lifespan unless it is re-initialized (with SetDoc or Load). As elements are added and removed to a CMarkup object, an existing element's index remains valid unless it is removed or replaced.