patch space

( n.)

   An  unused  block  of  bits  left in a binary so that it can later be
   modified   by   insertion   of  machine-language  instructions  there
   (typically,  the patch space is modified to contain new code, and the
   superseded  code  is  patched  to contain a jump or call to the patch
   space). The near-universal use of compilers and interpreters has made
   this term rare; it is now primarily historical outside IBM shops. See
   {patch} (sense 4), {zap} (sense 4), {hook}.

[glossary]
[Reference(s) to this entry by made by: {patch}]