Although the outlines of an expanded Home Affordable Refinance Program are far from clear, MBS analysts say the most likely changes designed to help more borrowers take advantage of record low mortgage rates will not have a disastrous impact on the MBS market. Observers note that there are two ways to expand the potential HARP population: remove the existing chronological restriction (loans made prior to June 2009) or lift the current loan-to-value restriction of 125 percent. The chronological restriction is relevant because a lot of borrowers who have used HARP already could benefit from refinancing again because...