Related:

• Scott's second Law: When an error has been detected and corrected, it will be found to have been wrong in the first place.
  Corollary: After the correction has been found in error, it will be impossible to fit the original quantity back into the equation....
• Scott's First Law: No matter what goes wrong, it will probably look right.
  Scott's Second Law: When an error has been detected and corrected, it will be found to have been wrong in the first place....
• After an instrument has been assembled, extra components will be found on the bench.
• check n. A hardware-detected error condition, most commonly used to refer to actual hardware failures rather than software-induced traps.
  E.g., a `parity check' is the result of a hardware-detected parity error....