The code I provided deletes all templates in sasuser.  You could be modifying templates in all kinds of other ways that would not be deleted by this.  If you are using the default template path, and if you never make sashelp itemstore updatable, then it will clean out all modified templates.   I stand by my statement though that a modified template could not account for using old data, but perhaps you associated an old data set with an old template. I hope this helps. ... View more

Adding to what @chrej5am said, retain works reliably only with newly created variables. Variables that are already present in the input dataset(s) will be overwritten anytime a new observation is read. ... View more

Then I suggest a datastep to transpose instead. Not all records have 10 diagnoses, many will be empty, correct?  3 milllion x10 diagnoses - 30 million. Not a small amount but shouldn't cause SAS to crash...  ... View more