There is only one file type that uses the .UDCX extension:
Universal Data Connection File
Data source connection file originally used by Microsoft FrontPage, but now adapted for various Microsoft programs, including Excel and InfoPath; contains properties to connect to one or more data sources; includes a connection string and authentication information.
UDCX files are used to store and share data source connection information in collaborative business environments. For example, UDCX files may be stored on a company Microsoft SharePoint server to access common data sources.
The Universal Data Connection (UDC) format extends the specification in .ODC files to include support for multiple different types of data sources, as well as arbitrary connection types. UDCX files are saved in an XML format.
NOTE: Microsoft updated UDC file format to version 2.0 for use with Microsoft Office 2010 applications such as InfoPath, an information-gathering and collaboration application for businesses.
Updated: April 4, 2010