how to put SSML string into a seperate file

string Ssml =
    @"<speak version='1.0' " +
    "xmlns='http://ift.tt/1k6Kcb1' xml:lang='en-US'>" +
    "Hello <prosody contour='(0%,+80Hz) (10%,+80%) (40%,+80Hz)'>World</prosody> " + 
    "<break time='500ms' />" +
    "Goodbye <prosody rate='slow' contour='(0%,+20Hz) (10%,+30%) (40%,+10Hz)'>World</prosody>" +
    "</speak>";

how to reference it in c# if is in different file, i can do it in xaml but the syntax for  "<" is  different.

the above code is just inside  c#. a simple string literal assigned to string variable, is there any other way to do this.

I'm trying to learn speech synthesis for windows runtime but the is little to nothing documentation on the web. I alreaady tried that mva course.