DIP 1027--String Interpolation--Final Review Discussion Thread

[Lim]

In current DIP I found a thing called IdentifierExpression. I 
searched both discussion threads and D documentations, founded no 
result regarding what it is (if I didn't miss something).

Is it the same thing as C++ id-expression? Will there be any 
differences between the following versions of interpolation 
strings?

     string someString = "abc";

     auto versionA = i"$someString";
     auto versionB = i"$(someString)";