Computing systems may include peripheral devices. Peripheral devices may add to or change the functionality of the computing system. In many cases, peripheral devices are connected to the computing system using an interconnect. The interconnect may implement a standard bus protocol, such as any of the Peripheral Component Interconnect (PCI) family of bus protocols. Transactions transferred over the interconnect typically include at least an address, designating a destination for the transaction. Write transactions may also include data to write to the address. With some bus protocols, transactions may also include attributes. Attributes provide additional information about a transaction.