An early documented usage of "deprecate" in this sense is in Usenet posts in 1984, referring to obsolete features in 4.2BSD and the C programming language.
Features are deprecated, rather than immediately removed, to provide backward compatibility and to give programmers time to bring affected code into compliance with the new standard.
Notable reasons for deprecation include: A building code example is the use of ungrounded ("2-prong") electrical receptacles (UK English: "unearthed").
Thus, though ungrounded receptacles may still be available for legal purchase in a location where they are obsolete, they would generally be intended only for repairs to existing older electrical installations.
Some word usages that have acquired different connotations over time, such as gay or colored, may be deprecated as obsolete in formal writing.