This, for those as yet unaware of such a disadvantage, refers to discrimination against those whose surnames begin with a letter in the lower half of the alphabet.
【词汇突破】discrimination：歧视
alphabet：字母表
【主干识别】This refers to discrimination against those加定语从句
【其他成分】for those as yet unaware of such a disadvantage：插入语，可改写为：for those who are unaware of such a disadvantage as yet理解起来会方便很多;as yet至今;whose surnames begin with a letter in the lower half of the alphabet定语从句。
