Do check on to this link for knowing the process of outbound function modules in idoc's.......
Hope this helps u,
I am going ahead with an assumption that you have a standard Idoc basic type but you aren't sure as of how/where is it getting populated. I have seen transaction WE41 which is an outbound process code but I have never used it when I worked on the outbound interfaces.
I would recommend that you go to SE11 give one of the segment names in the data type and display it. Then use a where-used-list to find out which program is using this segment. This should give you results.