The accurate measuring of overall form or details of the design to ensure that the desired effect is achieved. Numerous architectural elements had to be carefully planned so that they would fit with their neighbouring elements and measuring point are sometimes found on them. Likewise, measuring points are found on Roman statues. These are usually assumed to indicate that they were copied from models but it is also possible that these points were simply used by the carver as aids for the laying-out of designs. Rulers and set squares existed in the Roman period but most carvers probably used callipers for most measuring.