A faking technique where a complete piece is built by combining a new top onto an old authentic base, called Jie-di in Chinese.
This is usually found with a convincing authentic footrim (but usually a bit beat up) with the top and body covered with a new looking glaze.
On a vase for example, the piece might have an odd shape because the faker have built the vase on top of a base that used to belong to a bowl.
Monochromes, especially with blue glaze, are the most common for these jie-di pieces, because it is easy to hide the joint with blue glaze. To look for this, use a strong flash light to check the base to see if there is any evidence of an unusual joint around this area.
On temmuko pieces this is in my view usually impossible to discover, and you will need to look for other aspects and features that could signal age or authenticity for those wares.