From the 'AIDA Control' tab select 'Discriminator control'
From the 'Discriminator controls' tab
select FEE64 required
select (or deselect) 'Act on ALL FEE64 modules?' as required
select ASIC channel(s) to mask
The current default value (set by AIDA Settings) is 0x0 (no fast discriminator masks defined)
ASIC channels commonly masked include #2 (AS0 01) and #55 (AS3 06)