10.1—(1) This Part deals with the procedure for filing an acknowledgment of service.
(2) Where the claimant uses the procedure set out in Part 8 (alternative procedure for claims) this Part applies subject to the modifications set out in rule 8.3.
(3) A defendant may file an acknowledgment of service if—
(a)he is unable to file a defence within the period specified in rule 15.4; or
(b)he wishes to dispute the court’s jurisdiction.
(Part 11 sets out the procedure for disputing the court’s jurisdiction)