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Editing document I have found out, that Amaya generates and multiplays empty <none /> elements like shown below. <math xmlns="http://www.w3.org/1998/Math/MathML"> <mmultiscripts> <mi class="chem">U</mi> <none/> <none/> <none/> <none/> <none/> <none/> <none/> <none/> <none/> <none/> <none/> <none/> <none/> <none/> <mprescripts/> <none/> <none/> <none/> <none/> <none/> <none/> <none/> <mn>235</mn> <none/> <none/> <none/> <none/> <none/> <none/> </mmultiscripts> </math>