Cultural objects and China export restrictions
(3) above means that the export of any cultural item can be prohibited if the government thinks it has any high cultural or research value in view to craftsmanship, etc., even if it is more recently made.
(4) means that if you have an antique item that would be permitted according to antique export regulations, but another government department has restrictions (for example export restrictions on a type of wood, metal or other material), then an item cannot be exported even if it were allowed in view to the antique export regulations.
With other words, you can never be completely sure that you can export an antique craft or art object. And, apparently there have been cases where antiques less than 100 years old were not allowed out, simply because their age and craftsmanship resembled those of antiques from 100 years ago.
Internal Trade Prohibitions
As of now the domestic trade of cultural relics or antiques handed down as family heirlooms, ancestor's collections or otherwise is permitted internally.
However, trading of excavated items is not allowed at all. The meaning of this is that any and all excavated items, whether from tomb or kiln sites is strictly forbidden. Therefore, in Chinese auctions it is virtually impossible to see very old items, like Tang dynasty or older ceramics, in Chinese auctions, because items of those periods can impossibly be handed down until today.
For local collectors this means they can sell or buy any such items only illegally, "under the table".
To foreign buyers this means that anything from eras that old and offered from within China is probably a fake.
There are exceptions to the above, though. Anything that has a wax seal (or jianding seal) from one of the 'cultural relic stores'(Chinese: Wenwuguan) may be exported, even if it is over 100 years old. Obviously, they let you only export items that are plenty, or have little historical, cultural or artistic value.
Update November 2019:
It appears that now the upper age limit of cultural relics than can be exported is at 50 years (only); this means that virtually no real antiques are allowed out anymore, currently.
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