BCursor(const void *cursorData)
case 1:	cursorData is NULL =>
	empty cursor object (useless)
case 2: cursorData points to valid data =>
	valid cursor object
case 3: cursorData points to invalid data =>
	empty cursor object (useless)

BCursor(BMessage *archive)
case 1: archive is NULL =>
	empty cursor object (useless)
case 2: archive points to a valid archive =>
	empty cursor object (useless, R5 does not support archiving)

static BArchivable *Instantiate(BMessage *archive)
case 1: archive is NULL =>
	returns NULL
case 2: archive points to a valid archive =>
	returns NULL (R5 does not support archiving)

status_t Archive(BMessage* into, bool deep = true)
case 1: into is NULL =>
	returns B_OK
case 2: into is a valid message =>
	returns B_OK (archiving not implemented in R5)

status_t Perform(perform_code d, void* arg)
case 1: arg is NULL =>
	returns B_OK
case 2: arg points to something =>
	returns B_OK