This paper deals with a complete invariant ∆ X for cyclic quotient surface singularities. This invariant appears in the Riemann Roch and Numerical Adjunction Formulas for normal surface singularities. Our goal is to give an explicit formula for ∆ X based on the numerical information of X, that is, d and q as in X = X(d; 1, q). In the process, the space of curvettes and generic curves is explicitly described. We also define and describe other invariants of curves in X such as the LR-logarithmic eigenmodules, δ-invariants, and their Milnor and Newton numbers.