The Belgian flag retained the original saltire design through changes of lettering and oval. The earlier American Petroleum flag was white with Dutch national colours running from upper hoist to lower fly and Belgian colours from lower hoist to upper fly, beneath a white diamond with black APC. Most sources outline the diamond black; Talbot-Booth does not. Reed’s A.P.Co., with raised o and a stop beneath it, seems incorrect to Rosanoski. After the war blue Esso replaced the lettering. He does not establish whether the Belgian company retained its own flag until the end or adopted the common group flag.
Keep the explicit scope label independent; no alias or company identity is inferred.