This International Document specifies the general requirements applicable to legally relevant software-related functionality and security in measuring instruments and gives guidance for verifying the compliance of an instrument with these requirements. This Document shall be taken into consideration by the OIML Technical Committees and Subcommittees as a basis for establishing specific software requirements and procedures in OIML Recommendations applicable to particular categories of measuring instruments (hereafter termed “relevant Recommendations”). The instructions given in this Document apply only to software-controlled measuring instruments or their components. Note 1: This Document does not cover all the technical requirements specific to software-controlled measuring instruments; these requirements are to be given in the relevant Recommendation, e.g. for weighing instruments, water meters, etc. Note 2: This Document addresses some aspects concerning data security. In addition, national regulations for this area need to be considered.