HAMP HANDBOOK 4.4
The Making Home Affordable Handbook, version 3.0, dated December 10, 2010, was a big help.
Now we are up to Making Home Affordable Handbook 4.4, released March 3, 2014. It is a wealth of information.
It only applies directly to non-GSE loans, which means loans not owned by Fannie Mae or Freddie Mac, which is only around 30 percent of residential loans. However, Fannie and Freddie generally follow the guidelines, although they can deviate from them whenever they please.
You can look up your lender and find out if it has signed up with the Feds and is cooperating with the Making Home Affordable program.
There are more good references in the Links-Docs section of this site.