Here is what Rand Miller wrote about this: "Notice the smaller than normal pupils (barely noticeable) indicating D'ni blood... It's Gehn, almost as if he's watching you from the start, hmmmmmm... (Added by Richard Vander Wende when he put together that sequence.)"
Cho is the name given by Cyan to the first man you see on Riven, because the first word he says is "cho." Mark DeForest Write this: "Cho was instructed by Gehn to watch the caged linking spot in case someone (Gehn hoping for Atrus) will show up. When someone does, Gehn also instructed Cho to say a few D'ni phrases. However, Cho has been watching the cage for a *long* time and really thinks that no one will ever show up. Then you link in, surprising Cho but in a way he is excited to see someone new and starts talking to you in Rivenese. Then Cho remembers that he is suppose to say a D'ni phrase that he has memorized (but not too well, its hard to get good help). After messing that up, he decides to do the next thing on Gehn's list, which is to take any linking books. But of course, with the help of the rebel, he screws that up too."
This was answered by Richard A. Watson:
"What Cho says: tahg-em-ah... re-ko-ah (stutters) tah... tah... tah... tahg-em-ah b'soo re-ko-ah
translates roughly to: give-you (command) the-'ko-ah' (whatever that is).... gi... gi... gi... give-you (command) to-me (not pronounced quite right) the-'ko-ah'
What he's 'supposed' to say: tah-ge-mah b'zoo ah re-kor
give-you (command) to-me the-book.
which is: Gimme that book!"
Riven was the 5th Age that Gehn wrote, and during his long imprisonment there Gehn had become obsessed with the number 5, but the number wasn't otherwise special to the Age of Riven, nor was the D'ni culture obsessed with it. As Richard A. Watson put it, "Five is special to D'ni in the many of the same ways that 10 is special to us. Gehn just blew it way out of proportion, trying to connect everything around him to five."
That was one of Gehn's scribes, played by Tony Fryman, Cyan's President.
Edited from original source: D'ni Desk Reference