black art n. [common] A collection of arcane, unpublished,

black art n.

[common] A collection of arcane,
unpublished, and (by implication) mostly ad-hoc techniques
developed for a particular application or systems area (compare
black magic). VLSI design and compiler code optimization were
(in their beginnings) considered classic examples of black art; as
theory developed they became deep magic, and once standard
textbooks had been written, became merely heavy wizardry. The
huge proliferation of formal and informal channels for spreading
around new computer-related technologies during the last twenty
years has made both the term `black art' and what it describes
less common than formerly. See also voodoo programming.