(1) A party may make an offer to settle in whatever way that party chooses, but if the offer is not made in accordance with Rule 154, it will not have the consequences specified in this Part.
(2) In this Part —
(a) "Part 18 offer" means an offer made pursuant to the procedure set out in this Part;
(b) a "trial" means any trial in a case whether it is a trial of all issues or a trial of liability, quantum, or some other issue in the case;
(c) a trial is "in progress" from the time when it starts until the time when judgment is given or handed down;
(d) a case is "decided" when all issues in the case have been determined, whether at one or more trials;
(e) "trial Judge" includes any Judge allocated in advance to conduct a trial; and
(f) "the relevant period" means —
(i) in the case of an offer made not less than 21 days before a trial, the period specified under Rule 154(2) or such longer period as the parties agree; or
(ii) otherwise, the period up to the end of such trial.