Object selection
By selecting objects on a drawing, you can measure the length of objects which are CAD 'entities'. To do that, use ‘select objects’ as type of measurement and click OK.
On the drawing, mark the CAD objects whose length you want to measure by clicking on any part of them.
During a measurement, every object can be selected only once. This way you can avoid selecting the same object twice, and consequently including it twice in your measurement.
By using the ‘selecting objects’ option, you can only measure standalone CAD entities, while you cannot select/mark objects that are within a block.
During length measurement through object selection, you cannot select and measure the length of entities that belong to a block.