DSXchange

hii,
I am much new to DS - PX and going through documentation.

Following are my questions while going through it.

What is USS systems?
What is NLS?(National Language support)
What are SMP,MPP,Cluster system?

What is XML?
What is number of CPU licensed in context of installation?
What is user limit in context of installation?
what is stack in UNIX context?
what is ICU in context of NLS?
what is unicode?
what is RTI service?
What is diff between $ENV and $PROJDEF?
What is released job?
what is custom GUI Prog ID in custom stage?
what is difference between importing/exporting job executable against job component?

If these are not Interview question, most or all most all of the topic has been discussed in this forum.
Search for the same with appropriate keyword. If you dont find or difficult to find, revert back with correct topic and exact question.