[NTG-context] How to setup a headertext in a doublesided document in a cld?

Hello! I tried to setup a headertext in a context-lua-document. — No problem for the singlesided version, however hoe to pass the info for a double sided version? Unfortunately the cld-mkiv manual contains an example for a singlesided document. It ried context.setupheadertexts({ function() context("\\bf”) context.labeltext(monthname) context("\\hfill”) context(year) end}, {function() context("\\bf”) context.labeltext(monthname) context("\\hfill”) context(year) end}) but this is apparently not the good approach. Does someone of you have experience how to do this correctly? Kind regards Willi