An arc labelled a over-crossing one labelled b has jᵗʰ coordinate (-1)#92;frac#123;a#43;b-j#125;#123;2#125;#92;Delta#95;j#92;theta(a,b,j)#123;-1#125;A#123;a#43;b-j#43;(a²#43;b²-j²)#47;2#125; with respect to base #92;#123;#91;(a,b)j(a,b)#93;#92;#125;.
Source: wiktionary