nathe bit - which side does the plus sign go?

[frankfurt]

Hiya,

Am wanting to use a nathe on my horse which I bought ages ago - problem is I can't remember what the significance of the little plus sign (which appears on one side of the bit only, near the ring) is - does it mean it has to be on the right hand side of the horse's mouth? Any help much appreciated....

 

[k9h]

Not sure at all but I would think it went on the left so that you can see it when taking up???
What make is it??
Sorry not been much help!