Previous, if you wanted to exclude/override quoted items from Price Groups you had to create a Price Group manually.
With version 10.03, the Miva admin automatically creates the price group for you when you set up Manage Quotes.
To configure the price group, click on the Marketing heading and then click the Price Groups tab.
This functionality essentially locks a customer’s quote and does not allow them to manipulate the cart in any way to get additional discounts on their quote.
For example, you've already given the customer a discounted price in the admin via a quote, and you don't want the customer to also get a 10% sitewide discount promotion you are currently running. The Exclude Quotes from Price Groups functionality prevents that.