Reading the back sight range graduations on the Mk. 1 rear sight

According to the Knowledge Library, the back sight on my No. 4 Mk. 2 Enfield (UF 55 A17XX) is a Mark 1 back sight. As you are all well aware, the graduations are marked in yards from 200 to 1300. However, above each main yardage marking (2, 3, 4, etc.) there is a shorter line. As the range increases, the distance between this smaller line and the main range marking becomes greater. What is the use of the smaller range line? What does it signify, and how does the shooter use it correctly?

https://www.milsurps.com/images/impo...lxeqx0fv-1.jpg

Keith

I'd guess it's the +50 yards line

Yep, it's the 50 yard line