Thank you, Wolgang, that's it. Yesterday I tried also numbercommand, textcommand, etc. and the described problem did not appear. Why the key "command" needs \unexpanded and other keys (*command) not? Best wishes, Tomáš Mon, Mar 04, 2019 ve 06:50:27PM +0100 Wolfgang Schuster napsal(a): # Tomas Hala schrieb am 04.03.19 um 18:42: # >Hi all, # > # >compiling the ME below (ConTeXt from TeXlive) I got this error message: # > # >! Argument of \MyChapterCommand has an extra } # > # >and I do not know why. What am I doing wrong? # > # >Best wishes, # > # >Tomáš # > # >=================== # >\starttext # >\def\MyChapterCommand#1#2{::#1//#2==} # # Use # # \define[2]\MyChapterCommand{::#1//#2==} # # or # # \unexpanded\def\MyChapterCommand#1#2{::#1//#2==} # # Wolfgang