1, any type of value may be assigned to the type of unkown
2. If there are no type or type of assertion of the control flow based on the refinement may not be assigned to other unknown type, unknown at this time and it can only be assigned to any type of
3. If there is no type of flow control based on the type assertion or refinement, it can not carry out any operation on it
4.unknown with any other type of cross-type composition, and finally equal to other types,
5.unknown union type with any other type of composition, are equal to the unknown type, but any joint type only exception, unknown to any component equal to any
6.never type is unknown subtype
7.keyof unknown equal type never:
8. The only unknown to be like or different operations, other operations can not be performed
9.unknown type of value can not access its properties, create an instance of a class and as a function call:
10. If the type of traversed using a mapping type is unknown, it will not map any property