A term relating to publishers used when bidding on search engine keywords which includes an advertiser’s brand name, or phrases closely related to them.
Brand bidding is the practice of bidding on the brand terms of a third party, so your ads appear when their brand is entered as a search term. For example, an affiliate might bid on a brand term. The problem is the affiliate will grab traffic on the brand term and redirect it back to the brand and earn commission for it. Secondly, the cost of the brand's adwords campaign will go up.
This doesn't add value to the brand, hence, not allowed on DCMnetwork.