I design milking centers for dairy farms. This always involves a complex floor drainage plan. To place all of the concrete correctly, the concrete contractors I work with and I have relied on a plan sheet with spot elevations calling out the elevation of the floor at key locations. The elevation values are all relative to a plane projecting from a pre-existing slab or the top of a stake placed during site prep. The symbol I used in my old 2D cad software looks like a dowel pin symbol with a note (the elevation) attached. I have seen this symbol used on architectural plans (which is why I used it) but have not been able to find any solid information about conventions surrounding how the symbols are supposed to be used.
Is there any technique someone can suggest for producing a parametric value to use with a note or dimension that would in some way indicate the distance a vertex is from a reference plane so I don't have to calculate the value manually like I did in my old software?