Geoff Chappell - Software Analyst
When the IsOS function is given OS_TERMINALREMOTEADMIN as its dwOS argument, its answer is obtained by different methods in different SHLWAPI versions.
The modern implementation is simply to check the wSuiteMask member of the version information obtained from GetVersionEx. The function returns TRUE if VER_SUITE_TERMINAL and VER_SUITE_SINGLEUSERTS are both set.
Those builds of SHLWAPI versions 5.0 and 5.50 that support OS_TERMINALREMOTEADMIN instead check first that the system is a terminal server (through OS_WIN2000TERMINAL) and then consult the registry for whether the following value is zero:
This test is performed only when the function is first called for this case of dwOS. The function returns TRUE if the following are both true:
The OS_TERMINALREMOTEADMIN case of the SHLWAPI function IsOS is supported in version 5.0 from Windows 2000, and higher.