The mesonic chiral lagrangean of order p6

We construct the effective chiral Lagrangean for chiral perturbation theory in the mesonic even-intrinsic-parity sector at order p6. The Lagrangean contains 112 in principle measurable +3 contact terms for the general case of n light flavours, 91+3 for three and 53+4 for two flavours. The equivalence between equations of motion and field redefinitions to remove spurious terms in the Lagrangeans is shown to all orders in the chiral expansion. We also discuss and implement other methods for reducing the number of terms to a minimal set. (author)