@RainerK The function block declaration in Mervis requires the following schema but the INIT variable name to must not be used. This is a bug of course that needs to be fixed. But thanks for the info. I saw that you have already reported the issue via the Mervis report form.
FUNCTION_BLOCK fb_name (* EXTENDS //base type IMPLEMENTS //interface type list *) VAR (* add local variables here *) END_VAR VAR_INPUT (* add in variables here *) END_VAR VAR_OUTPUT (* add out variables here *) END_VAR (* METHOD abc //: return type // method's body END_METHOD *) (*function block body*) END_FUNCTION_BLOCK```R