What is this?

[Canonfodder]

Ladies & Gentlemen
Need a little help here. Bolting together a 1983 Holdsworth Mistral (not exactly an expert) and need to know what this lug/nipple on the right side of the downtube (looking from the riding position) is. It's about where I will site the downturn shifters so is it a guide, is it to be avoided at all costs, is it sent by the cycle God's to test me?

 

[biggs682]

its where the gear levers mount around the frame

 

[midlife]

Stops the banded shifters sliding down the frame...also found on the top like this.

Shaun

 

[Canonfodder]

Brilliant. As I suspected but wanted to make sure. Thanks for your replies guys.