Cannot create offsets for markpoints (ODU select option switches to TGPT instead)

[shagrat]

After you created a markpoint (MPD OSB "MK0-10") you can not create an offset for it.

To reproduce (tested in 2.8 MT):

- SSS down twice to activate DMT in TV

- slew DMT over any ground feature and designate

- press the OSB labeled "MK0" on the EHSD to create a markpoint (M0) or press multiple times to create M1-xx (tested with M1 as well)

- press and hold WINC or OSB option select until Quick Access menu is showing on the ODU

- select ":MKPT", enter No. on scratchpad ("0" the markpoint you have created), press "ENT" and verify the EHSD shows "M0" between the arrows

- press OSB "DATA" to edit the markpoint. ODU option 1 will show ":WYPT"

- press OSB select 1 and it will switch from ":WYPT" to ":TGPT"(!) instead of the correct ":WO/S".

It should be the same offset functionality, as is already implemented for waypoints. So if pressing OSB select 1 it should switch to ":WO/S" and show the "BRG", "ELEV", "RNG", "UTM" entries for the offset, not switch to ":TGPT" (as this is performed by selecting WYPT or WO/S and pressing DESG on the EHSD. 

I link a video (not mine) for details.

Discussion leading to this bug report here: Markpoint offset discussion

https://youtu.be/ErWQoFJzZ9A

Edited April 2, 2023 by shagrat
typos corrected