ALL DSP allows you to mask entities or attributes by type.

If you are working with multiple viewports, select the
viewport you want to mask in.

Indicate a masking method by choosing from the following 
options:

ALL - to select all displayed entities. If you are working
with multiple viewports, ALL selects all entities, 
including partially displayed entities, displayed in the
selected viewport that are allowed in that function. 

BY TYPE - to select the entities specified in any of the 
Masking Menus.

EX TYPE - to select all entities except those specified in 
any of the Masking Menus.
