All persons of working age who, during a short reference period, were engaged in any activity to produce goods or provide services for pay or profit. They comprise:
(a) employed persons “at work”, i.e. who worked in a job for at least one hour;
(b) employed persons “not at work” due to temporary absence from a job, or to working-time arrangements (such as shift work, flexitime and compensatory leave for overtime).
OIT 2013 - Resolution concerning statistics of work, employment and labour underutilization.