Thanks for picking this up and taking it over the finishing line, Valentin. LGTM apart from a couple of nits.
Trevor https://codereview.appspot.com/553750044/diff/561590043/Documentation/notation/staff.itely File Documentation/notation/staff.itely (right): https://codereview.appspot.com/553750044/diff/561590043/Documentation/notation/staff.itely#newcode1559 Documentation/notation/staff.itely:1559: to be explicitely printed, using the syntax described in explicitly https://codereview.appspot.com/553750044/diff/561590043/Documentation/notation/staff.itely#newcode1589 Documentation/notation/staff.itely:1589: it requires to be followed by a music expression: requires to -> must https://codereview.appspot.com/553750044/
