“. . . credit strategies . . . ” ???

My wife is a retired VA public school teacher, receiving a pension from the Virginia Retirement System (VRS). Yesterday we received the annual VRS Retiree News with a report of VRS financial performance for the past year.  Here’s a quote:

The VRS achieved a 15.7 percent net return on its investment portfolio for fiscal year 2014 . . .

The portfolio included $28.8 billion in public equity, $11.9 billion in credit strategies, $12.2 billion in fixed income, $7.0 billion in real assets and $5.1 billion in private equity, as of June 30, 2014.

I have some questions.

1.  I assume the 15.7 NET return means the VRS earned 15.7 % AFTER deducting fees, expenses, and other costs of doing business — right?

2.  What is/are “credit strategies?”  I understand public equity and fixed income but have not a clue about “credit strategies.”  Are these derivatives or some other shaky investment?

3.  What is “private equity?”

Thanks and Merry Christmas.