What are annotation elements in a Revit model?

Annotation elements in a Revit model play a crucial role in conveying information about the design, specifications, and other important details of the project. They include text notes, dimensions, tags, and markers, which serve to enhance the understanding of the model by providing contextual information. For instance, text notes can clarify specific design requirements or convey instructions, while dimensions depict measurements critical for construction. Tags help identify various components within the model, linking them to their properties or annotations.

In contrast, the other options highlight elements that do not align with the primary function of annotations. Structural elements pertain to the physical components of the model, while dimensions specifically are part of annotations but do not encompass all types as mentioned in the correct choice. Lastly, 3D models are primarily visual representations of design intent rather than informational aids, distinguishing them from the textual and qualitative nature of annotation elements.