Understanding and tokens

Authoring Inform 7
#1

I’m looking at the Remembering extension. I don’t quite understanding how this bit of the extension

Understand
"examine [any seen thing]" or
"x [any seen thing]" or
"look at/for [any seen thing]" or
[ other bits snipped ]
"where is/are [any seen thing]" as remembering.

interacts with the existing understands, e.g.,

Understand "examine [something]" as examining.

(from appendix A p131).

I can see that the token’s different, [any seen thing] vs [something].

So in this little example:

"expt1" by Phil932.
Include Remembering by Aaron Reed.
The Dull Place is a room.
The Boring Place is south of the Dull Place.
The emerald is in the Boring Place.  The description is "A green glowing thing."

I get

Dull Place
>x emerald
You can't see any such thing.
>s
Boring Place
You can see an emerald here.
>x emerald
A green glowing thing.
>n
Dull Place
>x emerald
You can't see the emerald any more.

which is the behaviour I want, but I don’t understand how it happens.

Can someone explain that to me, please? Is it simply that [something] is more specific than [any seen thing]?

TIA.

#2

[something] is the normal case, which matches any thing in scope. [any thing] matches any thing in the entire game. [any seen thing] matches any thing in the entire game which has the seen property.