Answer by Graham Dunnett

See here: http://msdn.microsoft.com/en-us/library/windowsphone/develop/e6883c06(v=vs.105).aspx This is a string compare function on WP8. The last argument is shown to be a `StringComparison` enum, whereas the JSON code appears to assume it's a `Boolean`. (Note that MSDN says there is a version of `Compare` which has a third argument of `Boolean`, but that's not part of .NET on WP8.)