Samsung PN51E6500EFXZA - Manual (Page 199)

For example, click the 18 ans+ lock
and you block all TV programs rated 18
ans+.
The rating categories are also grouped
so that clicking one category blocks
all the categories a parent would block
along with it. For example, if you block
the 8 ans+ category, then 13 ans+ , 16
ans+ and 18 ans+ will automatically be
blocked also.
N To unblock a category, click the lock