Subscripted form fields are not supported

IBM® Informix® 4GL forms can define subscripted fields with multiple field definition entries in the ATTRIBUTES section, each defining a piece of the data displayed by the field, as in this example:
DATABASE stores 
SCREEN
{
   1234567890
  [f01       ]
  [f02       ]
}
END
ATTRIBUTES
f01 = customer.cust_name[1,10];
f02 = customer.cust_name[11,20];
END

In the ATTRIBUTES section, the name of the field is immediately followed by a subscript specification defining the piece of sub-data the screen tag displays and allows to input.

This feature is not supported at all by Genero BDL, all fields must be defined as a whole.