Acoording to the materials of FWARC 2006/224, there are three mainly parts changed to support the type7c keyboards
1. SHIFT-PAUSE key sequence under both OpenBoot and Solaris to send "break"
2. NVRAM variable "keyboard-layout" added
The keyboard selection will be passed to Solaris in the NVRAM variable "keyboard-layout". This avoids the necessity of Solaris re-asking if the selection has already been made in OBP, as well as allowing Solaris to communicate the results to OBP if a selection or change is made while Unix is running.
3. The supported keyboard layouts are provided in OBP for the NVRAM variable.