All simple operations aimed at verifying the working conditions of an item of equipment, at preventing any breakdown and at solving those pertaining to the levels of maintenance 1 and 2. Note: The term "maintenance" also pertains to the preservation missions carried out by those who own the items of equipment.

Accounting	2
Agriculture	38
Alternative dispute resolution	26
American usage, not spelling	4
Antennas and waveguides	6
Austrian usage	1
Automatic control	2
Automobiles	26
Ball bearings	1
Banking	4
Basketball	2
Biology	7
Book binding	1
British usage, not spelling	13
Business	71
Chemistry	15
Coal	4
Communications	46
Computer numerical control	4
Computers	21
Construction	44
Cooking	2
Customs	6
Earth sciences	3
Economy	81
Education	8
Electronics	25
Employment	1
Engines	2
Environment	6
European Union	2
Figurative	15
Finances	41
Fish farming pisciculture	2
Food industry	6
Foreign trade	63
Game theory	1
General	1048
Gymnastics	2
Health care	6
Hobbies and pastimes	4
Human rights activism	9
Idiomatic	4
Industry	8
Informal	91
Information technology	17
Insurance	24
International Monetary Fund	2
International trade	2
Labor law	2
Law	63
Life sciences	6
Marketing	2
Materials science	3
Mathematics	1
Measuring instruments	4
Mechanic engineering	17
Medical	14
Medical appliances	6
Metallurgy	13
Microelectronics	40
Microsoft	12
Military	3
Mineral products	1
Mining	6
Municipal planning	5
Natural sciences	5
Non-governmental organizations	1
Obsolete / dated	2
Oils and lubricants	1
Optics branch of physics	45
Packaging	1
Patents	59
Pharmacy and pharmacology	2
Physics	6
Politics	6
Polygraphy	9
Power lines	3
Proverb	2
Punched cards	2
Quotes and aphorisms	1
Rail transport	1
Refrigeration	2
Religion	1
Rude	8
Sailing	1
Shipbuilding	1
Shooting sport	1
Slang	4
Social science	7
Sports	2
Statistics	9
Swimming	2
Table tennis	2
Taxes	13
Technology	154
Telecommunications	2
Telephony	1
Tennis	1
Textile industry	1
Trade unions	1
Transport	96
United Nations	8
Weapons and gunsmithing	7
Work flow	1
Wrestling	3