CAD Blocks

[ActCAD]

CAD blocks are named groups of objects that act as a single 2D or 3D object. They are used to create repeated content, such as drawing symbols or standard components.
Blocks help you to save time, maintain consistency and reduce file size by re-using and sharing content rather than re-drawing it every time you need it.
https://actcad.com/blog/cad-blocks/