As you familiar with BASE SAS then you will know of the dictionary tables accessible from SASHELP or the dictionary libraries. This SUGI paper details some of the nice additions to these in SAS 9: www2.sas.com/proceedings/sugi31/045-31.pdf
In terms of metadata typing in 'Metabrowse' into the command line window of your BASE SAS session will give you an idea of what is available. There are many objects. 'Metafind' is also a good one, should you know the metadata ID. For more details on getting into the metadata you should have start to have a look at: http://support.sas.com/onlinedoc/913/getDoc/en/omags.hlp/a003160218.htm
There is alot to read on the area. When changing metadata it would be recommended to always use the GUI tools available to you.
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