Hi:
Also, as for the difference between PROC CONTENTS and PROC DATASETS. I think of PROC CONTENTS as an "information-only" procedure. It reports on the contents of a SAS dataset.
PROC DATASETS goes one step beyond "information-only" -- it can also produce a report on the contents of a SAS datasets, but that is merely a by-product of its more powerful ability to do things like modify a SAS dataset, delete a SAS dataset, rename a dataset, change labels or formats, etc. PROC DATASETS is what I call a "utility" procedure -- for example, let's say I create a dataset with a bunch of variables and I forgot to add labels and formats -- I could go back and reread the input file all over again, but with PROC DATASETS, I can make those changes to the descriptor portion of the SAS file without going back and rereading the original input file. The documentation on PROC DATASETS is quite thorough and the overview gives a better description than I have:
http://support.sas.com/documentation/cdl/en/proc/59565/HTML/default/datasets-overview.htm
cynthia