DCL, the DIGITAL Command Language, is the standard command languageadopted by most of the operating systems that were sold by the former Digital Equipment Corporation (which has since been acquired by Compaq which itself was acquired by Hewlett-Packard). It had its roots in the IAS, TOPS-20, and RT-11 operating systems and was implemented as a standard across most of Digital's operating systems, notably RSX-11, but took its most powerful form in the OpenVMS operating system.