As I mentioned my macro saves the data inside the macro body. The macro body is simple page content. So you if you want to create a new entry, you parse the XHTML/storage format of the page, find your macro, enter a new entry into it’s body tag and then save the modified XHTML.
Of course you could also create your own table or something like that. However then you have some other problems to deal with like how would you delete the data of a macro if it’s been removed from a page, etc.
As I said, storing your macros data inside its body has a lot of benefits and probably also makes the most sense since your data is always “linked to your macro”. But if you rather store it elsewhere you can of course do so.