The use of any standard is always voluntary.
The medical device directive 93/42/EEC, transposed into national law, is the law! As such, it is the Essential Requirements of the MDD that must be met.
Usually, the most straightforward way to show that you have satisified the Essential Requirements is to use the applicable technical standards, including EN1041 (for Information Provided).
Note that, at the moment, it is EN 980 that is listed as the 'Symbols' standard.