The legislation, HR 4170, would amend the Higher Education Act of 1965 by giving borrowers the option to enter the 10/10 loan repayment plan. Discretionary income, in this case, appears to be defined as any annual income exceeding 150 percent of the poverty line for an individual or family.
The legislation also would cap interest rates on federal loans at 3.4 percent, and allow graduates who enter public service professions -- such as teaching and firefighting -- to have their loans forgiven in five years instead of ten.

http://www.govtrack.us/congress/bill.xpd?bill=h112-4170