This is from the article discussed in another thread talking about Bly but here you are:
"Also, the Redskins reworked the contracts of Portis and star wide receiver Santana Moss, converting large portions of their 2007 base salaries to bonuses, which become guaranteed but can also be prorated for cap purposes. The players lose no money in the transaction, and Portis's cap figure went from $7.1 million to $4 million, according to sources, while Moss's charge was lowered from $5 million to $3.2 million."
washingtonpost.com