This is a permanent feature. This feature exists since the first versions of BDL/Genero.
BTW: See this example. This example inverts the feature. The Informix compiler can see the lines between "--#{" and "--#}" as code. The Genero compiler sees the same lines as comment.
DEFINE a1, a2 DYNAMIC ARRAY OF INT
--#{
allocate ARRAY a1[10] -- not visible for Genero, visible for i4gl
--#}