Haircuts and holding periods

[shanlane]

I know that treatment of collateral is not gone into too heavily on the exam, but I was reading through the main Basel II document and when it discussed collateral haircuts it kept mentioning a 10 day holding period. For instance, a AAA soverign with a maturity of greater than 5 years has a standard haircut of 4%, based on a 10-day holding period. What exactly is this "10 day holding period" referring to?

Thanks!

Shannon