An RVT-R Reader is a development system that highly resembles a retail unit, but has a green cover in front.
Revolution OS identifies this as
Emulation platform (10000002) with 88MB of memory.
IOSes installed on 1.0U reader
A reader running 1.0U was found with IOS4v3, IOS9v516, IOS10v518, IOS11v10, IOS12v6, IOS13v10, IOS14v257, IOS17v512, IOS21v514, IOS30v1039, and IOS31v1039. The HackMii Installer is unable to run due to the ES_GetTicketViews hack only working on newer IOSes, and possibly timing issues in older IOSes; however, it appears to reload between IOSes without issues.
Two additional channels exist: a disc tool and a tool to uninstall the System Menu. There are also two additional preinstalled channels (with files in /meta): 0144434b (.DCK) and 01574d55 (.WMU), which presumably correspond to these channels.
Content IDs appear to be allocated randomly, resulting in content IDs like the one for IOS4v1. However, there is probably a pattern, since titles from different regions seem to share content IDs.
RVT-R discs appear to be writable by licensed developers with special burning hardware, although this hardware has not been used by homebrewers, and the structure of the discs themselves are not known. It may be possible to recover this structure from the RVT-R Reader drive firmware.
Blank discs can be identified by the data side being in a more blue hue. Attempting to dump a blank disc with CleanRip yields glitchy chars on the screen, and the disc does not dump.