But I wasnt sure that using a description column to describe the data was the right way to go, because you could then put any type of data in the same table.
Wouldent that break the rules of normalization?
The point of normalization is to describe data in such a way that you can manipulate it with SQL. A description column or a comments column tends to defeat that: you can't manipulate English text with SQL.
But if all you want to say is, "the English description of this domain is 'description'," and all you'll ever want to do is read it or set it, that's (at least) in 1NF. It's a judgment call you have to make.
Incidentally, you'd probably want to just one description for each domain. So it ought to be a column of domain_data rather than split off in its own table.