This is included in the MPN signed by every federal student loan recipient:
"Public Service Loan Forgiveness A Public Service Loan Forgiveness (PSLF) program is also available. Under this program, we will forgive the remaining balance due on your Direct Loans after you have made 120 payments (after October 1, 2007) on those loans under certain repayment plans while you are employed full-time by a qualifying employer. The required 120 payments do not have to be consecutive. Qualifying repayment plans include the REPAYE Plan, the PAYE Plan, the IBR Plan, the ICR Plan, and the Standard Repayment Plan with a 10-year repayment period. Note: Although the Standard Repayment Plan with a 10-year repayment period is a qualifying repayment plan for PSLF, to receive any loan forgiveness under this program you must enter the REPAYE Plan, the PAYE Plan, the IBR Plan, or the ICR Plan, and make the majority of the 120 payments under one of those plans."
Hope this clears things up for you!
edit: you can read the whole contract here!
https://studentaid.gov/mpn/subunsub/landing