

B. E. Roys proposed a flag on 19 January 1903: a white lozenge with J.C.J.L. letters between red at the hoist and blue. It was adopted, then changed within months to red above and blue below, relating it to the Dutch flag. Jarig Bakker’s account instead explains the original colours through KPM’s white diamond on red and KNSM’s white diamond on blue, with the new initials replacing the royal crowns. That account gives use of the initialled flag as 1902–47.
Sources differ over whether the funnel mark is a panel or a band. Brown 1943 specifies a band, as does Ships & The Sea, and a photograph of De Schelde could support that appearance, while Wij Varen Weer shows a panel. Talbot-Booth and Harnack split the letters into JC and JL with a gap.