• Data reference period (Month)
• Geographic localization (Mainland)
• Sex

• REFERENCE PERIOD:  The length of time for which data are collected, e.g. a specific day, month or year.
• LOCAL UNIT:  An enterprise or part thereof (e.g. a workshop, factory, warehouse, office, mine or depot) situated in a geographically identified place. At or from this place economic activity is carried out for which ' save for certain exceptions ' one or more persons work (even if only part-time) for one and the same enterprise.

The average monthly earnings is calculated by: Sum Xh(RBm+SBm+TSm)/ TCOm, where m is a generic index defined by intersection of the occupational level variable and sex variable, RB is the total basic remuneration paid to TCO, SB is the total regular bonuses and allowances/grants paid to TCO, TS is the total overtime remuneration paid to TCO, TCO is the number of employees, Xh is the estimator of the total defined in paragraph 28 of the methodological document Earnings and working hours survey.