Tracer lamina are small-scale features appearing in the vertical profiles of long-lived tracers such as ozone and modified potential vorticity. Appenzeller and Holton <1997> diagnosed the production of tracer laminae from satellite data and assimilated fields using a quantity which they referred to as the tracer lamination rate (L). Subsequent studies with L have shown that this diagnostic must be treated with some caution. Two limitations of L calculated from low-resolution horizontal data have been identified and are discussed here. First, L calculated from low-resolution data does not refer to scales at which laminae are formed, and second, on the scales at which L is relevant there is a reversible contribution, due to the propagation of planetary waves. This reversible contribution is demonstrated using a simple model of a steady stationary Rossby wave. The magnitude of the reversible component is estimated from data and found to be a significant fraction of the L calculated from low-resolution data. ¿ 1999 American Geophysical Union