Marking a scale on a measuring instrument. This involves establishing the relationship between indications of a measuring instrument and standard or reference quantity values, which must be applied.
For example, placing a thermometer in melting ice to see whether it reads zero, in order to check if it has been calibrated correctly.
e.g. Clive finds some old mercury thermometers, but the scales have worn off over the years. He doesn't want to throw them away as they appear to work very well. He decides to calibrate them.
Filling a beaker with ice and a little water, he lowers the thermometers into the mixture. Using a permanent marker, he marks a line on the thermometer to show the freezing point of water (0°C)
Clive then boils a beaker of water and places the thermometers into it. Again he marks the level of the mercury in the tubes (100°C)
Once cool, Clive carefully measures the distance between the marks, which is 20.0 cm.