In CVS and Windows snapshot you can do the following (revised version of Ignacio's sample script): <script> function sillyfun (string foo, series x) series @foo_f1 = x+x(-1)+x(-2)+x(-3) series @foo_f2 = x+x(+1) list outlist = @foo_f1 @foo_f2 return list outlist end function open data9-9 string sname="nocars" list alist = sillyfun(sname, nocars) print alist </script> Alternatively, you could give the string argument to sillyfun as a quoted string literal: list alist = sillyfun("nocars", nocars) This should also work in the GUI function-caller. In that case you type something into the string parameter slot: if it's the name of an existing string, it gets used as is; if it's not the name of a pre-defined string it is treated as literal, and is automatically wrapped in quotes if it's not already quoted.