Problem of dysplaing varchar variable

I encountered a problem of displaing varchar variables with null or "" values. Is it a bug? Can i bypass the problem? Below i attached nulls.4gl and nulls.per files to demonstrate the problem. Thanks in advance, Vadim -------------- nulls.4gl ------------- main define rec record str varchar(250), str1 varchar(250) end record # one of the following commented LET statements spoil # a display produced by display statement at line A # moreover, first LET spoils displaying rec.str1 for INPUT on line B # when DISPLAY on line A is commented #let rec.str=rec.str1 #let rec.str="" open form nulls from "nulls" display form nulls display rec.* to s_rec.* # A input rec.* without defaults from s_rec.* # B end main -------- corresponding nulls.per --------- DATABASE formonly SCREEN { Display varchar with NULL:[A1 ] [A2 ] } ATTRIBUTES A1 = formonly.str type varchar, color=reverse; A2 = formonly.str1 type varchar, color=reverse; INSTRUCTIONS screen record s_rec (formonly.str, formonly.str1) delimiters " "