ExportData to an already created Custom Export File

Hi- I'm currently working on a plugin right now, and everything seems to be working, however I'm having an issue with exporting data after storing and stopping. We have a custom export file that has already been created, and I would like to be able to export to the already created export type. I understand that for the ExportData function, the first parameter is the integer value for the Export Type, however, on the list of Export Types, the number on the list is 16, but the Export Type said is it out of range for that. Is there another way to access that Custom Export other than the integer? Or is there a way to assign that Export Type an integer value? The custom export type is a text file, but customized, and since I just started with this project, I have no idea what was used to create the custom export file type. Any and all help will be appreciated. Thanks, - Steve L. -