I read on forbes.com:
It can be difficult for investors to know the true cost of individual bonds on the secondary market, as prices frequently include markups. In addition, it’s entirely possible to see the same bond offered by two different dealers at two different prices. You may also be charged commissions, transaction fees and contract fees on your bond-related transactions. [emphasis mine]
What's the difference between markups and "commissions, transaction fees and contract fees" when purchasing individual bonds on the secondary market? I thought it was the same, but I'm not familiar with it.