legal ground
Article 400 of the Civil Code
To establish a mortgage, the parties shall conclude a mortgage contract in writing. A mortgage contract generally includes the following clauses:
(1) The type and amount of secured creditor's rights;
(2) The time limit for the debtor to perform the debt;
(3) The name and quantity of the mortgaged property;
(4) the scope of the guarantee.
Article 402
Where the property specified in Items 1 to 3 of the first paragraph of Article 395 of this Law or the building under construction specified in Item 5 is mortgaged, the mortgage registration shall be handled. The mortgage is established at the time of registration.