Currently, if I define a function like: .. function func ( series a, scalar b[1:2:1], bool c[1], list d[null]) .. I'm supposed to be able to call the above-mentioned function with something like: .. a = uniform() a = func(a) .. and Gretl is supposed to assign the default values to the scalar b and the boolean c, and at the same time, gretl should tolerate the absence of the list d as parameter. The logic is "I omitted the parameters because I know what I'm doing". Currently, Gretl complains about the lack of the parameters func: not enough arguments Command has insufficient arguments where the error is due only to the absence of the list. I know that the [null] identifier in the definition of the function means that the list may be empty (not missing) but actually the script works fine even without the [null] tag when any empty list is passed. So, it might be thought to tolerate missing parameters if the absence doesn't compromise the usability of the function itself. Obviously some convention should be introduced on the subject. The same idea could be valid for series and matrix as well. I know this feature-request is not a top priority, but I just wanted to point out something that could be useful to extend the gretl scripting capabilities. Cheers, Stefano