With the Dimension command selected justd keep selecting linework in elements, components or detailed and reference linework to create a continuous dimension. Continuous dimesnions act as one object and cannot be exploded or their dimensional value edited. You can relocate where the dimension text is positioned, the extension line offset and dimension line. Dimesnions in Revit are always positioned or placed on component or linework and cannot be arbitrarily placed in coordinate space as AutoCAD dimesnions.
Mel Persin, AIA
AEC Technology Consultant
Technology to Visualize and Realize Solutions