TsctlSystemAPICountDesc
From embeddedTS Manuals
This function returns the number of API functions implemented in the specified class . The value returned is one greater than the maximum value allowed to be passed as the instance parameter in any tsctl protocol request to the specified class; if a value equal or greater is passed, the server will signal an exception by closing the connection to the client.
If the server does not have any instances of the specified class, the value returned will be 0.