5.13.3 ‘@:’: Pseudo-colon

‘@:’ is an invisible colon (see Pseudo-operators). It can be helpful in formatting certain C constructions correctly. For example, if one has a named module defined as

@<Cases@>=
case 1:
case 2:
case 3@: @;

then one can use it as a case construction followed by the usual colon, as in

switch(c)
        {
   @<Cases@>: 
        stuff;
        break;
        }