I am trying to loop a command over a list of nonsequential values.  The command would ideally open two files, indexed by the values, so e.g first_22 and second_22; first_28 and second_28, etc. and then, after some data manipulations, save the resulting file as FinalFile22, Finalfile29. Unfortunately the following line produces an error.    set mylib."first_&value";   I have tried various places to put the dots and the quotation marks, all of which eventually produce an error of some sort.  The sketch of the code is below.   I would appreciate any help with this.    %macro aaa(values); %let count=%sysfunc(countw(&values)); %do i = 1 %to &count; %let value=%qscan(&values,&i,%str(,)); libname mylib '/project/this/data'; data FirstData; set mylib."first_&value"; [...] data SecondData; set mylib."second_&value"; [...] data project.FinalFile&value; set Finalfile;run; %end; %mend; %mtaq(%str(22,28,34));   ... View more