IEC TS 61994-4-4:2018 is available as IEC TS 61994-4-4:2018 RLV which contains the International Standard and its Redline version, showing all changes of the technical content compared to the previous edition.

IEC 61994-4-4:2018 gives the terms and definition for single crystal wafers for surface acoustic wave (SAW) devices representing the state of the art. This edition includes the following significant technical changes with respect to the previous edition:
- the new terms and definitions given in IEC 62276:2016 have been taken into account;
- the general title has been changed according to the change in the title of TC 49 in 2009.
- the part title has been changed according to the title of IEC 62276:2016.