Gray vs. Grey

メイルを書いていて，ふと，graylistingなのかgreylistingなのかで迷った．手元にあった"Oxford American Dictionary"(Eugene, Ehrlich et al. Avon Books, 1982)¹を見たら，

grey = gray

と書いてあり，どちらでも間違いでは無いらしい．"The Difference Between Gray and Grey"(Bernie Zimmermann)には，

According to Google Answers, the two words have almost the same meaning in all cases, and g-r-a-y is simply an American derivation of the original spelling g-r-e-y. According to Flak Magazine, the difference can be chalked up to the same happenstances that led to organize/organise and judgement/judgment.

とあるので，grayがアメリカ式，greyが英国式の表記のようだ…