http_defaultCGI always changes file extension to .htm

I want to use http_defaultCGI to download a file called default.csv. Its fine, and works OK, but somewhere along the way the file extension changes to .htm.

I can work around this, but is there another way ?

The HTTP_BT.lib:
This function should not be called directly by the
application. It is intended to be used as a new-style
CGI for handling file uploads.

             See "samples	cpip\http\upld_fat.c" for an example
             of using this function.

Are you using this directly in your code?