Since z/VSE 4.3 we support 4 digit device addresses. During the IPL process 4 digit device addresses, called physical (device) addresses, are mapped to 3 digit addresses, called VSE (device) addresses. The mapping can be defined via the IPL ADD statement. After IPL complete z/VSE uses VSE device addresses. You may display the mapping of the device address with our IUI dialogs or the Attention Routine command QUERY IO. QUERY IO accepts as input a physical device addresses or VSE device addresses - or you may display the mapping of all added devices. You may display groups of devices too, if you just query for the first digits of the device address, e.g. QUERY IO,CUU=FF displays all devices that start with FF.
You may have noticed, that we added a new PF key to the z/VSE console - 11=PCUU. If you just press PF11 and your cursor is in the command line, you will get "%EXCUU 28". Therefore you need to position the cursor to a device address on your console, hit the PF11 key and the QUERY IO command with the device address appears in your command line. Just hit enter and you will get the mapping of the device. You can also use the PF11 key, if you can't remember the syntax of the QUERY IO command. Just position the cursor to a reply id (number after the partition id) of any message on your console and hit the PF11 key. The command appears in your command line and you may overwrite the device address (CUU=) or use QUERY IO,CUU=ALL to display the mapping of all devices.
The QUERY IO command is described in the z/VSE System Control Statements book, It's available on our documentation web page.