How to you boot/reboot in single user mode on Suse 12 Enterprise Server. On the 3270 console I am at the SLES12 advanced options screen.

GNU GRUB version 2.02~beta2 Use the ^ and v keys to select which entry is highlighted. Press
enter to boot the selected OS, `e' to edit the commands before
booting or `c' for a command-line. ESC to return previous menu.
*(3) SLES12, with Linux 3.12.39-47- default
(4) SLES12, with Linux 3.12.39-47-default (recovery mode)
(5) SLES12, with Linux 3.12.28-4-default
(6) SLES12, with Linux 3.12.28-4-default (recovery mode)

I enter ^N to select the next option.
(3) SLES12, with Linux 3.12.39-47-default
*(4) SLES12, with Linux 3.12.39-47-default (recovery mode)
(5) SLES12, with Linux 3.12.28-4-default
(6) SLES12, with Linux 3.12.28-4-default (recovery mode)
The system does not come up in single-user mode. It seems to take the default mode and ignore the recovery mode.
There is an edit mode but not sure how to edit. There is also a command mode but I am not sure what the proper command and syntax would be.

Speak to SuSE - there doesn't seem to be a whole lot of doco on the z implementation of grub.

Well, this was not easy to figure out. Hard to edit on a 3270 console. I needed to issue a lot of key combinations to perform he edit. I entered 'e' to get intp edit mode on the selected entry. Then I enter ^N a few times to move down to the line I needed to edit. This was the line that started with 'linux'. I entered ^E to move to the end of the line and the I entered ^O to open the line. I added the word 'single' not enclosed with the '. Finally entered ^x to boot. I was able to get into maintenance mode. Another method was to edit the /etc/default/grub file and add 'single' to the parameters: GRUB_CMDLINE_LINUX_RECOVERY="hvc_iucv=8 TERM=dumb noresume x11failsafe crashkernel=204M-:102M single". With this method you need to update the kernel with the command:grub2-mkconfig -o /boot/grub2/grub.cfg.