The measure in dots (mizan)
The mizan is the measure of the letters in dots: the dot, the mark the pen leaves when drawn its own width, is the unit, and the alif is the yardstick.
The dots stand corner on corner in one upright column, each on the highest corner of the one below, to the right of the alif.
The Studio's measure, read on the masters' sheets, is Naskh 5 dots, Thuluth 7, Ruq'ah 3, Diwani 6 with a line after the third, and Farsi 3; Kufi is not measured in dots.
Ibn Muqla or his brothers are considered the originators of the proportioned script, in which a letter's design is related to the size of the dot and the height of the alif.
The measure is an aid to the beginner: a guide, not a ruler.
In Mashq Studio
Trace and every lesson draw the alif's measure as a column of dots beside the letter, and each script's path and practice pages show its figure. Open the Studio, free.
Where Mashq Learn teaches it · Free practice sheets
Other terms: Qalam, the reed pen · Tashkeel, the Arabic diacritics · Kashida (tatweel) · the glossary
Sources: Mashq Studio — ops/MIZAN.md · Wikipedia — Ibn Muqla