Using the option Labels present in the View menu (and also in the right mouse button menu), user can see the numeric id of some entities of the model. Either for points, lines, surfaces or volumes user can choose between viewing the labels of all the entities, or just the selected ones.
In the following figure the model can be seen with the number of some entities:

As it can be seen, the colors of the numbers of the entities follows the philosophy of the colors of the entities in GiD (volume numbers are in light blue, surface numbers are in pink and so on).
In order to get a better visualization set the render mode to normal when showing labels.

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