What type of GC is used in PLT?

[Thomas Wager <twager@mac.com>]

Hello everybody,

I am wondering what type of GC PLT uses (especially in v200 for MacOS 
X)? As far as I know from the Unix port by default a conservative GC is 
used, with the option to build a VM with a precise GC (which is more 
portable).
Conservative GC is said to produce large "memory leaks" in the long run. 
Is this a) true? b) true if I do not use any foreign C code but "only" 
Scheme?
I would appreciate it very much if someone could shed some light on 
this, or point me to any further documentation.

Thanks!

Thomas