The RIBA Plan of Work depicts the design and construction process, the contributions made to the process by various participants and the exchange of information between them. By understanding the design process, it is easier to understand where measurement fits into the ‘big picture’ and how models that seek to measure or quantify the design develop as the design progresses. Different procurement methods dictate when, in the design process, measurement takes place, and who performs the measurement function. In some cases, contractors undertake measurement tasks that were once the sole province of the professional quantity surveyor. Constructors are aware that designs convey little more than the designer's intent and BIM models greatly assist in the visualisation and quantification of designs through the medium of 5D BIM.