I've been using playerglobal.swc of flash player 11 and SDK 3.6.
ReferenceError: Error #1065: Variable JSON is not defined
can be solved by setting -swf-version to 13. (http://forums.adobe.com/message/3933620#3933620)
However, swf-version is not available in SDK 3.6.
Can native JSON be used?
Otherwise, can com.adobe.serialization.json.JSON be used without name conflict?
JSON (from ...\flex_sdk_3.6\frameworks\libs\player\11\playerglobal.swc(JSON))
com.adobe.serialization.json:JSON (from ...\as3corelib.swc(com/adobe/serialization/json/JSON))