All indexes that are
created for a particular data set are stored in one file in the same
SAS library as the data set. You can use PROC CONTENTS to print a
list of all indexes that exist for a data set, along with other information
about the data set. The CONTENTS statement of the PROC DATASETS step
can generate the same list of indexes and other information about
a data set.
Many of the maintenance
tasks that you perform on your data sets affect the index file that
is associated with the data set. When you copy a data set with the
COPY statement in PROC DATASETS, the index file is reconstructed for
you. When you rename a data set or rename a variable with PROC DATASETS,
the index file is automatically updated to reflect this change.