Commands operate in either model space or in paper space. You use model space using
the Model tab to do design and drafting, creating 2D or 3D models. You use paper space
(a named layout) to create a layout, possibly with multiple views of a drawing, for
plotting.

When you are in a layout, you can enter MSPACE at the Command prompt to make the last
viewport in the layout current. You can then pan and zoom in model space in that layout
viewport to adjust the extents and scale of the view and change the layer display
properties.