The disease that stood at the pivotal crossroads of oncology was yet another rare variant of leukemia called acute promyelocytic leukemia—APL. 2010, Siddhartha Mukherjee, The Emperor of All Maladies, Fourth Estate (2011), page 407:
(abbreviation, alt-of, countable, initialism, qualifier:scouting) Initialism of assistant patrol leader.
An early programming language using mathematically derived symbols for many of its operations.
The language APL presents a number of novel problems for a compiler writer: weak variable typing, run time changes in variable shape, and a host of primitive operations, among others. 1988, Timothy Budd, An APL Compiler, Springer, →ISBN, page 1:
(abbreviation, alt-of, initialism) Initialism of Adaptive Public License.