The GetExtensionVersion function is the first entry-point function in IIS. This function allows your ISAPI extension to register its version information with IIS.
BOOL WINAPI GetExtensionVersion(
Points to an HSE_VERSION_INFO data structure that your extension has populated with your extension's version information.
GetExtensionVersion must return TRUE for IIS to be able to use your ISAPI DLL. If this function returns FALSE, IIS will not use the extension.
IIS calls this function when the DLL is initially loaded, and the call is made in the system's security context.
Client: Requires Windows XP Professional, Windows 2000 Professional, or Windows NT Workstation 4.0.
Server: Requires Windows Server 2003, Windows 2000 Server, or Windows NT Server 4.0.
Header: Declared in httpext.h.