17. Sometimes, a change to the data type can affect a program's ability to run or fail. For example, changing a field from a character to a numeric would cause a program to fail if the program exhibited what? 18. Does a database display data to a user (or present to a program) in a logical or physical data format? Or both? 19. Under what DBMS function, the database still handles all of the physical data characteristics but hides that complexity from the users and programs? 20. Where does the DBMS store meta data