Use communication:amateur_radio:repeater:dcs=* to assign the DCS activation code of a amateur radio repeater.
The DCS activation code is a 3-digit octal number.
DCS (Digital-Coded Squelch) is commonly known as CDCSS (Continuous Digital-Coded Squelch System). This system adds a 134.4 bps (sub-audible) bitstream to the transmitted audio to open receiver audio output. In amateur radio repeaters this starts re-transmission of received signal as well. More details can be found at wikipedia:Digital-Coded Squelch.