The Web Service Enhancements are a software library created by Microsoft to enable .Net programmers to kick start development of low-level web service functionality. The library supports many of the functions in the GXA.

From Microsoft:
"Web Services Enhancements 1.0 for Microsoft® .NET (WSE) provides advanced Web services functionality for Microsoft Visual Studio® .NET and Microsoft .NET Framework developers to support the latest Web services capabilities.

Web Services Enhancements 1.0 for Microsoft .NET is the released and supported version of the Web Services Development Kit Technology Preview (WSDK)."