Record Management Services (RMS) are procedures in the VMS, RSTS/E, RT-11 and RSX-11M operating systems that programs may call to process files and records within files.
[1][2] Its file formats and procedures are similar to of those in some IBM access methods[a] for several of its mainframe computer operating systems[b] and by other vendors for file and record management.
VMS RMS is an integral part of the system software; its procedures run in executive mode.
(RMS was not initially integrated into RT-11 and RSTS/E, but was available as an added charge "layered product".
RMS supports four record access methods: RMS supports four record formats: Digital provided the File Definition Language (FDL) which could be used to define the structure of an RMS file.