What does merging .... Do?

I'm using JASSnewgen, and I was just wondering what the options "Merge Object Editor Data" and "Merge Constants Data" do under the Extensions menu. I didn't want to go trying it myself and risk messing something up. Thanks!

You can import object editor data and gameplay constants/game interface settings with it.
Unlike the import option in the object editor it doesn't replace the current data, but simply adds the new data to the existing stuff.

The Export option in the Extensions menu does the opposite and allows to export the settings to a file.

Oohh, I thought it was like an optimizing thing, to save space or whatever. Thanks.