Within the Spot Dimension tool you can choose between spot elevations and spot coordinates. Spot Elevations will report the elevation of certain objects. Spot Coordinates will report the distance and direction of a point from an origin that you define (see Tools, Shared Coordinates... Specify Coordinates at a point)
While Spot Coordinates will report the coordinates of any model or drafting element it is not really clear in the help files that Spot Elevations will report the elevation of only certain parts of model elements. Here is the list of elevations that Spot Elevations will tag:
- roof eaves and ridges
- stair steps and landings
- window sills and door thresholds
- tops of footings & beams
- the sill and head of openings in a wall
- any point within the area of (non-sloping) floors and ceilings
- the height of a family's model objects (provided they are visible in the view)
- apparently ramps too but I haven't figured this one yet
- if you know of any more please add a comment
Taging the elevation of a horizontal surface won't work in wireframe mode. Spot Elevations may be deleted when trying to modify some objects in certain ways.
Two interesting parameters in the properties dialog are Relative Base and Elevation Origin. If you go to the type properties and change the Elevation Origin to Relative you will notice that the Relative Base instance parameter is no longer greyed out. You can now report the elevation of a point relative to any level you've created.
One nice thing about all Spot Dimensions is that you can control the units format separately from the project's units format by going to the type properties dialog so that their units display in decimal feet if you wish. It would be nice if levels had the same ability.