Hi Hans, is it intended that you used the same names for \left and \right in the defintions below? \installmathfencepair \ulcorner \Luppercorner \ulcorner \Ruppercorner \installmathfencepair \llcorner \Llowercorner \llcorner \Rlowercorner \installmathfencepair \lmoustache \Lmoustache \lmoustache \Rmoustache \installmathfencepair \llbracket \Lopenbracket \llbracket \Ropenbracket \installmathfencepair \lgroup \Lgroup \lgroup \Rgroup Wolfgang