Sorry, las reply was wrong
stream.InvokeVoid("Write", text)

byte[] content = (binary content of exported xml file)
string flags = "/compile=1"

var iris = IRIS.CreateIRIS(cn);
string text = System.Text.Encoding.UTF8.GetString(content);
IRISObject stream = (IRISObject)iris.ClassMethodObject("%Stream.GlobalCharacter", "%New");
stream.InvokeVoid("Write", text);

iris.ClassMethodStatusCode("%SYSTEM.OBJ", "LoadStream", stream, flags, errorlog);

byte[] content = (binary content of exported xml file)
string flags = "/compile=1"

var iris = IRIS.CreateIRIS(cn);
string text = System.Text.Encoding.UTF8.GetString(content);
IRISObject stream = (IRISObject)iris.ClassMethodObject("%Stream.GlobalCharacter", "%New");
stream.InvokeVoid("Write", content);

iris.ClassMethodStatusCode("%SYSTEM.OBJ", "LoadStream", stream, flags, errorlog);