Each of these commands reads two or more input files and combines them.
The command's output becomes the new active dataset.
None of the commands actually change the input files.
-Therefore, if you want the changes to become permanant, you must explictly
+Therefore, if you want the changes to become permanent, you must explicitly
save them using an appropriate procedure or transformation (@pxref{System and Portable File IO}).
The syntax of each command begins with a specification of the files to