Alarm Decoder KPM Messages - Fixed Length?

Simple question (I hope)...
Are Keyboard messages (KPM messages) sent from the AD2xxx device a fixed length message? I know the length will increase if you set the CONFIGBITS KPM Prefix switch to true. I have looked at the Protocol reference but can't determine if the "Raw Data" portion of the message is variable length.
Thanks.
Are Keyboard messages (KPM messages) sent from the AD2xxx device a fixed length message? I know the length will increase if you set the CONFIGBITS KPM Prefix switch to true. I have looked at the Protocol reference but can't determine if the "Raw Data" portion of the message is variable length.
Thanks.