M marking may only be fixed together with the ‘CE’ marking to non-automatic weighing instruments which meet the requirements of the directive 2014/31/EU and 93/42/EEC as amended by 2007/47/EC and which were subject to conformity assessment procedures. 
The (III) marking is based on International Organization of Legal Metrology (OIML) & is identified as Class 3 accuracy. The above mentioned markings are mandatory for EU nations, for other nations these markings are non-mandatory.
NAWI stands for Non-Automatic Weighing Instruments. Weighing instruments used for medical weighing have to comply with the requirements of the NAWI directive 90/384/EEC. The directive is implemented in the UK by the Non-automatic weighing Instruments Regulation 2002. Under these regulations, the design of medical weighing instruments must be approved by a notified body, and all products from the production line must be individually verified for conformity and accuracy by a Trading Standards officer or other approved verifier. Each instrument must be covered by a Declaration of Conformity and bear the "" label indicating conformity with the Directive and the Regulations.