Tables don't exist outside of text frames when you use InDesign. You may come from a Quark background where they are separate, but not ID. That said, I don't understand your question.
What do you mean they don't exist outside of text frames? I create a separate text box and create a
table in it. How else would I get a table to stretch across a 2 column layout in InDesign?
Read Scott's advice in one of your other threads...
But beyond that, tables are somewhat unique in ID. They can be stretched to extend beyond the frame edge of the text frame that contains them.
Have you ever used QuarkXPress? Many people who use InDesign have, and in fact, many have migrated to InDesign from Quark, and ask things from a Quark perspective. In Quark, there is a table tool that creates free-standing tables. In InDesign, tables are created inside of text frames. In Quark, you can create a free-standing table, and anchor it in text like a graphic, but InDesign can't make a table outside of a text frame.
When you asked about tables with the phrase "in and out of text threads," my first thought was that you were talking about free-standing tables.
I told you the steps in your other thread. I have more experience with CS3, which didn't have the "Span Columns" command, so I told you how to do it the way I knew how, although you got better advise from Scott. And by the way, you don't need a separate box just to have a table stretch across two columns, but but it does allow you to wrap text in the other column around the table.