What is the sliding bar on the bottom of my road shoe for? I recently ordered some Sidi Scarpe Zephyr Cycling Road Shoes.

Absolutely fit perfectly, however I've noticed there is a sliding bar element on the bottom of the shoe and I cant work out what it is for.

I'm going to fit some look delta cleats on them, for use in the velodrome.

Best explanation is it has the standard look cleat holes, 3 main holes in a triangle shape. However there is one vertical slot (about 2cm) in the middle of the 3 holes, that has a sliding mechansism within it, i cant work out what it is for.
Seems that is the Look Memory Eyelet, where you can attach some kind of tab to help get replacement cleats in the same position.

This Keo page seems to have a video on the subject, but I can't view it immediately ...