Am 14.03.2015 um 09:36 schrieb Qi Shi: > ? list X=dummify(Z5) --drop-first >> list X=dummify(Z5) --drop- > The symbol 'drop' is undefined > > Error executing script: halting >> list X=dummify(Z5) --drop-first > " > > why did i encounter the error? > You're mixing up the 'dummify' command with the 'dummify()' function. Only the command takes these double-dash-style options like "--drop-first". For the function you have a second argument, please see the help for that (haven't used it myself yet). Remark for Allin and Jack: BTW, I think the error message is strange insofar as IMO the parser should complain already about the "--" in there, not about the "drop" word, no? But perhaps this has been changed since last release.