#### 6.7.3 Lists of variable names

To refer to a set of variables, list their names one after another. Optionally, their names may be separated by commas. To include a range of variables from the dictionary in the list, write the name of the first and last variable in the range, separated by `TO`. For instance, if the dictionary contains six variables with the names `ID`, `X1`, `X2`, `GOAL`, `MET`, and `NEXTGOAL`, in that order, then `X2 TO MET` would include variables `X2`, `GOAL`, and `MET`.

Commands that define variables, such as `DATA LIST`, give `TO` an alternate meaning. With these commands, `TO` define sequences of variables whose names end in consecutive integers. The syntax is two identifiers that begin with the same root and end with numbers, separated by `TO`. The syntax `X1 TO X5` defines 5 variables, named `X1`, `X2`, `X3`, `X4`, and `X5`. The syntax `ITEM0008 TO ITEM0013` defines 6 variables, named `ITEM0008`, `ITEM0009`, `ITEM0010`, `ITEM0011`, `ITEM0012`, and `ITEM00013`. The syntaxes `QUES001 TO QUES9` and `QUES6 TO QUES3` are invalid.

After a set of variables has been defined with `DATA LIST` or another command with this method, the same set can be referenced on later commands using the same syntax.