Every ship becomes eligible for a periodic inspection as follows: (1) High Risk Ship (HRS): between 5 and 6 months after the last inspection in the PMoU region; (2) Standard Risk Ship (SRS): between 10 and 12 months after the last inspection in the PMoU region; (3) Low Risk Ship (LRS): between 24 and 36 months after the last inspection in the PMoU region. The time span for the next periodic inspection re-starts after any inspection.