The publication of the National Occupational Classification (NOC) 2021 is the thirtieth anniversary of the standard occupational classification system and it introduces a major structural change. The NOC 2021 Version 1.0 overhauls the "Skill Level" structure by introducing a new categorization representing the degree of Training, Education, Experience and Responsibilities (TEER) required for an occupation. The NOC 2021 Version 1.0 also introduces a new 5-digit hierarchical structure, compared to a 4-digit hierarchical structure in the previous versions of the classification. The NOC has been developed and maintained as part of a collaborative partnership between Employment and Social Development Canada and Statistics Canada. This revision is extensive; the last structural revision was NOC 2011.