For adjustable storey markers there are 3rd party objects available (some may be free, others - $$$).
But I am not sure if they allow you to add levels that are not actual storeys.
I am sure someone has created an object to show additional levels - it is just a matter of finding it.
You could just add your own text - but of course it would not be linked to heights of elements if they change.
Or you could use the elevation/height label (I can't remember what it is called - there may well be both).
The label can be customised to show what you want and it will link to the heights of elements.
One of the forum moderators.
Versions 6.5 to 25
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