Lumenzia: Mask Modes
The various preview buttons (such as D2, Z3, ...) can be set to several alternative modes as noted below.
Live mask mode creates layer masks immediate as the various mask creation buttons are clicked. This offers a rapid way to see how various masks will blend. This option is only availabe on Photoshop CC.
Live selection mode creates luminosity selections immediately as the various mask creation buttons are clicked. This allows for faster work when painting through selections for exposure blending and dodging/burning.
BlendIf masking mode allows you to create any standard/zone mask or zone/range picker as a BlendIf. This saves significant file space, and avoids the need to fix or recreate layer masks if you change the underlying pixels (for cloning, dust spot removal, etc).
CS6 users should hold <shift> while clicking the mask creation buttons in order to use BlendIf:under (or <shift>-<ctrl/cmd> for BlendIf:this).