...
Hotkey: Shift+Backspace
Only available in Paper Space, displays the entire drawing sheet. The drawing sheet may consist of multiple printer paper sheets, indicated by dashed lines.
...
Note: Zoom diagnostic message appears when the user tries to zoom in or zoom out beyond the maximum zoom factor or limit.
...
Zoom Selection
Hotkey: Alt+Backspace
Zooms to an area that completely contains all currently selected objects.
...