(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 give extra diagnostic output, the programmer might just add a test for some otherwise meaningless feature of the existing 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.
Try this search on Wikipedia, OneLook, Google
Nearby terms: hi « HIBOL « HID « hidden flag » hierarchical database » Hierarchical Data Format » Hierarchical Design Methodology