The Free On-line Dictionary of Computing (30 December 2018):

Data Management Language

    (DML)

   1. Any language for manipulating data or files,
   e.g. IBM's Distributed Data Management (DDM).

   2. An early ALGOL-like language with lists and graphics,
   that ran on the Honeywell 635.

   ["DML: A Data Management Language", D.W. Bray et al, GE,
   Syracuse NY].

   (1999-06-07)