@:: 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;
             }