DP CON ALIASPARAMETERS

From Quake Wiki

Indicates this engine supports aliases containing $1 through $9 parameter macros (which when called will expand to the parameters passed to the alias, for example alias test "say $2 $1", then you can type test hi there and it will execute say there hi), as well as $0 (name of the alias) and $* (all parameters $1 onward).