selection-mode-append-switch

See this command in the command table.

Home ribbon >> Select >> Append (toggle).
Using the command line, enter "selection-mode-append-switch" and press ENTER.
Display the Find Command screen, locate selection-mode-append-switch and click Run.

Command Overview

Determines how data is selected or deselected in response to data selection in combination with the CTRL key.

There are two selection modes available:

Enabled: if data is selected by any method with the CTRL key held down, it is added to the selection pool if it was not already selected. Data cannot be removed from the selection pool.
Disabled: data within the selection boundary will reverse its current state; selected data becomes unselected and vice versa.