Part VI
Mutual legal assistance in criminal matters
CHAPTER III
Special forms of international assistance
Article 158
Transit
1. The provisions of Article 43 shall apply mutatis mutandis to the transit of any person who is under custody in a foreign State and who must appear in the territory of a third State in order to take part at criminal proceedings.
2. Custody of a person in transit shall not remain if the State that authorised the transfer requests the person to be set free.
Transit proceedings
Transportation and transit through State territory for surrender
EDIT.