Switch channel strings and switch relay strings identify a specific channel or relay of a switch. These strings are typically used when an operation or query is performed on the switch-connect, disconnect, find path, and so on. These strings are constructed in very similar fashions.
You can find the switch channels and switch relay strings in LabVIEW and LabWindows/CVI from the switch I/O name control. The name control should list valid channel/relay names for your current switch hardware configuration.