Multi Mapping question

I have seen how it is possible to do 1:n message mapping with Multi mappings.

http://help.sap.com/saphelp_nw2004s/helpdata/en/42/f3b31d48fb1bc8e10000000a11466f/content.htm

If I do this, and I use a file adapter for the created message, will I get one message per file, or will all of the messages exist in one file?

BR,

Tony.