The fire resistance classes measure the time in which a part retains its full functioning in case of a fire. Such functions may include the sustainability, thermal insulation and smoke consistency. In line with DIN 4102, the following fire resistency groups are determined: F for walls, ceilings and supports, T names fire barriers such as doors, gates and dampers, F,G for fire-resistant glazing, R for pipe openings. The fire rating for the various parts is measured in minutes. The abbreviation F-90 means that a fire protection wall has a fire restistance duration of 90 minutes.