The IRCS of a fishing vessel is its radio call sign.Vessel markings shall be painted with marine coating. Characters of the Chinese vessel name shall be block letters, and the numbers may be Arabic numerals. Characters of the English vessel name, CT numbers and the IRCS shall be capital letters and Arabic numerals. The height, width, and colors of characters shall meet the specifications as shown in Appendix 10.Appendix 10 Specification of Width, Height and Color of Characters for Vessel Markings .pdf