Many Chinese clans have a "昭穆", a kind of poem from which each generation of the clan picks a successive character as a prefix to given names, so we can easily identify people from one generation to another. For instance, I am of the "性" generation according to my clan's "昭穆". Now, the "昭穆" contains this sentence:
黃中元吉迪,青簡大名留。
According to this page, "黃中" would mean "being employed as an imperial government official" or "having a career in the imperial government" ("在朝為官"). However, I have been unable to find further reference to back up that interpretation. I have even looked up the character "黃" in the 《古漢語常用字字典》 and the closest thing I get is "[matters] related to the Emperor", with no direct mention of "government" or "officials".
Would somebody with good knowledge in classical Chinese be able to enlighten me?