(scientific computation) An extra option added to a routine without changing the calling sequence. For example, instead of adding an explicit input variable to instruct a routine to giveextra diagnostic output, the programmer might just add a test for some otherwise meaningless feature of theexisting inputs, such as a negative mass. The use of hidden flags can make a program very hard to debug and understand, but is all too common wherever programs are hacked in a hurry. [ef="module.php?name=Lexikon&file=search&eid=1&query=Jargon File">Jargon File] (1994-11-24)