Civil Service Personnel Rules Rule 234

234. The longest term of service of a service personnel for pension purposes shall be from the date the person had attained the age of 18 up to the time of retirement. After attaining the age of 18, the following periods are counted in the term of service qualifying for pension in addition to the period of performing duties out of service:
(a) paid apprenticeship;
(b) probationary period;
(c) joining time;
(d) temporary suspension while on duty;
(e) suspension which is entitled to enjoy for pension although the service personnel is not treated as on duty;
(f) other periods when the service personnel is treated as on duty.