function _fnAjaxDataSrcParam(settings, param, json) {
		var dataSrc = $.isPlainObject(settings.ajax)
			? settings.ajax.dataSrc
			: null;

		if (dataSrc && dataSrc[param]) {
			// Get from custom location
			return _fnGetObjectDataFn(dataSrc[param])(json);
		}

		// else - Default behaviour
		var old = '';

		// Legacy support
		if (param === 'draw') {
			old = 'sEcho';
		}
		else if (param === 'recordsTotal') {
			old = 'iTotalRecords';
		}
		else if (param === 'recordsFiltered') {
			old = 'iTotalDisplayRecords';
		}

		return json[old] !== undefined
			? json[old]
			: json[param];
	}
Very similar to _fnAjaxDataSrc, but for the other SSP properties
@param {*} settings DataTables settings object
@param {*} param Target parameter
@param {*} json JSON data
@returns Resolved value