My brother in law just got a lease to sign for his upcoming apartment, and one clause of the addendum states that
"The tenant agrees to not record this lease. Any recording or attempted recording will constitute a breach of this lease."
(not sure if i have the wording exactly)

By "record," I assume they mean something along the lines of

Main Entry: 1re·cord
Pronunciation: ri-'kord
Function: verb
1 a (1) : to set down in writing : furnish written evidence of (2) :to deposit an authentic official copy of <record a deed>

Questions:
1) Why would a tenant want to "record" a lease?
2) Why would a landlord want to prevent recording a lease (for instance, tax avoidance or something even shadier)?
3) Is it even legal to prevent recording? The apartment in question is in Pennsylvania.

Thanks,
-steve