ITU‐T's Technical Reports and Specifications 763 Figure 1 – Dimensions of KPIs for SSCs 6.2 Sub‐dimensions of KPIs The sub‐dimensions for each dimension are recorded in Table 1 and explained in the succeeding subsections. In Table 1 each dimension is identified by the letter Dx. The sub‐dimensions are then classified by the label Dx.y where x maps to dimension and y maps to sub‐dimension. Table 1 – Sub‐dimensions of KPIs Dimension # Dimension Sub‐dimension # Sub‐dimension D1 Information and communication technology D1.1 Network and access D1.2 Services and information platforms D1.3 Information security and privacy D1.4 Electromagnetic field D2 Environmental sustainability D2.1 Air quality D2.2 CO2 emissions D2.3 Energy