A system for validating, using a procedure checklist, that a procedure is followed by an operator, comprising: - the procedure checklist printed over a markable support, comprising: - a first element printed thereon comprising a first graphical assemblage; - a second element printed thereon comprising a second graphical assemblage that is different from the first graphical assemblage; - a first marking tool adapted to generate markings that permanently alter in a visually verifiable manner the markable support matching the first graphical assemblage, wherein the first marking tool is provided at a first location associated with the first element of the procedure checklist, the first marking tool bearing a first identification specific to the first location allowing to provide a one-to-one relationship between the first location and the first marking tool; and - a second marking tool adapted to generate markings that permanently alter in a visually verifiable manner the markable support matching the second graphical assemblage, wherein the second marking tool is provided at a second location associated with the second element of the procedure checklist, the second marking tool bearing a second identification specific to the second location allowing to provide a one-to-one relationship between the second location and second marking tool, wherein the operator following each of the first and second elements of the procedure checklist uses the respective first and second marking tools at the respective first and second locations to generate markings on the markable support, and wherein following of the procedure is validated by comparing the first and second markings generated on the markable support using the first and the second marking tools with the first graphical assemblage and the second graphical assemblage. - the procedure checklist printed over a markable support, comprising: - a first element printed thereon comprising a first graphical assemblage; - a second element printed thereon comprising a second graphical assemblage that is different from the first graphical assemblage; - a first element printed thereon comprising a first graphical assemblage; - a second element printed thereon comprising a second graphical assemblage that is different from the first graphical assemblage; - a first marking tool adapted to generate markings that permanently alter in a visually verifiable manner the markable support matching the first graphical assemblage, wherein the first marking tool is provided at a first location associated with the first element of the procedure checklist, the first marking tool bearing a first identification specific to the first location allowing to provide a one-to-one relationship between the first location and the first marking tool; and - a second marking tool adapted to generate markings that permanently alter in a visually verifiable manner the markable support matching the second graphical assemblage, wherein the second marking tool is provided at a second location associated with the second element of the procedure checklist, the second marking tool bearing a second identification specific to the second location allowing to provide a one-to-one relationship between the second location and second marking tool, wherein the operator following each of the first and second elements of the procedure checklist uses the respective first and second marking tools at the respective first and second locations to generate markings on the markable support, and wherein following of the procedure is validated by comparing the first and second markings generated on the markable support using the first and the second marking tools with the first graphical assemblage and the second graphical assemblage.