I think I've just answered my own question. Here's what I wrote to an online geologist:

"During the last week, I've read many articles on the Internet about the Hadean Era. The specific phrase "pre-Isuan sequence" keeps coming up on several sites in relation to Mr. Cloud's having named the era. I realize that Isuan ('Izuan') is an early geologic period. But what I cannot find is any information about what this 'sequence' is--the so-called 'pre-Isuan sequence.' Does that simply refer to the series of periods subsumed by the Hadean Era that precede the Isuan (Izuan) period?

Thanks in advance for the favor of a reply."

*Thanks Et', Cap' and Jack'--your information definitely confirmed what I'd collected.