Interesting article on the Core Technology of DLP - Protection of the Data (regardless of the device or file) "A Reverse Content-Aware FirewallTM prevents the loss of confidential or protected data (including IP or trade secret information) from your network to the Internet over a whole range of network protocols, applications, data formats and usage scenarios. An attempted data leak is blocked, even if the protected data was altered from its original form through format conversion, copying, extracting, embedding, re-typing, compression, file extension changes etc."
Cited from GTB Technologies website "Core Technology of DLP - Protection of the Data (regardless of the device or file) " http://www.gtbtechnologies.com/en/company/about/core-technology