In Java memory management, what does 'PS' stand for?

Whenever I see reference to memory in Java, the various spaces are always prefixed with 'PS'. What does 'PS' mean? It's starting to bother me... my only guess so far is 'pool space', but that would be redundant.

Examples:

• PS Eden Space
• PS开发者_如何学JAVA Survivor Space
• PS Tenured Space (Old Generation)
• PS Perm Gen (Permanent Generation)

I could be wrong but i'm pretty sure it stands for Parallel Scavenge (has to do with garbage collection)

Improving Java Application Performance and Scalability by Reducing Garbage Collection Times and Sizing Memory Using JDK 1.4.1: Parallel Scavenge Collector