What is limit for user and kernel space after enabling /PAE option in server?

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http://serverfault.com – By default in 32 bit system, 2 GB is allocated to user space programs and 2GB for kernel space programs. Now, if we add /3GB option in boot.ini user and kernel space get respectively 3 and 1GB. But what happens when we enable /PAE, then how user and kernel and user space are allocated? (HowTos)