The Key Mask function allows temporary activation or deactivation of the remote inputs of SC Net devices and their connected keys, depending on the requirements.
In the Media Pool, click the plus sign next to category 
Devices.
From the device folder All devices drag Special functions into a marker track.
Right-click the marker, select Properties and the dialog will appear.
Click Key Mask to specify the corresponding remote input:
For Sub address you enter the range, i.e. 1 for remote inputs and 2 for IR keys. See also Remote Properties of Shows.
Under Mode you can choose the way the Key Mask is to be changed.
Set ...to set the mask and overwrite old masks. Here the following applies: 1 = remote input is enabled and 0 = remote input is disabled.
Or ...enables the remote input in the current mask; 1 enables a remote input, while 0 causes the current status to be maintained.
And ...disables the remote input in the current mask; 0 disables a remote input, while 1 causes the current status to be maintained.
Under Mask you can enter the values for the 16 first inputs the mask is to be changed with. This is done in groups of four, starting with input 1...4, 5...8, 9...12 and finishes with 13...16. More than 16 remote inputs cannot be influenced via the Key Mask function.
In field Comment you can enter any appropriate designation to become visible in the timeline. Usually it makes sense to enable option Auto comment, which generates some suitable labelling depending on the function chosen.
Finish by clicking on OK.
For information about the other functions refer to Special functions for the SC Master.