zz = .NULL. ? ISNULL(zz) ---> .T. ? STR(zz,5) ---> Error: Function argument value, type, or count is invalid ? STR(.NULL.,5) ---> .NULL. ? zz+"AA" ---> Operator/Operand type mismatch ? .NULL. + "AA" ---> .NULL. ? NVL(zz+"AA","xxxxxx") ---> Operator/Operand type mismatch ? NVL(zz,"xxxxxx") ---> "xxxxxx" USE myTable REPLACE c1 WITH .NULL. ? c1 + "AA" ---> .NULL. SCATTER MEMVAR ? m.c1 + "AA" ---> .NULL. zz=c1 ? zz + "AA" ---> .NULL. zz = .NULL. ? zz + "AA" ---> .NULL. RELEASE zz zz = .NULL. and all the errors returnWhy do variables directly assigned .NULL. not seem to work correctly while fields and SCATTERed variables give the expected results?