// basic routines:
TAG * swf_InsertTag(TAG * after,U16 id); // updates frames, if necessary
+TAG * swf_InsertTagBefore(SWF*swf, TAG * before,U16 id); // like InsertTag, but insert tag before argument
int swf_DeleteTag(TAG * t);
void swf_ClearTag(TAG * t); //frees tag data