You can use the LABEL=
option on both input and output data sets. When you use LABEL= on
input data sets, it assigns a label for the file for the duration
of that DATA or PROC step. When it is specified for an output data
set, the label becomes a permanent part of that file. The file can
be printed using the CONTENTS or DATASETS procedure, and modified
using PROC DATASETS.
A label assigned to
a data set remains associated with that data set when you update a
data set in place, such as using the APPEND procedure or the MODIFY
statement. However, a label is lost if you use a data set with a
previously assigned label to create a new data set in the DATA step.
For example, a label previously assigned to data set ONE is lost when
you create the new output data set ONE in this DATA step:
data one;
set one;
run;