  Correlations of like-sign pion pairs emerging from proton-antiproton
collisions are analysed in the two-dimensional (q_L,q_T) decomposition of the
three-momentum difference q. While the data cannot be adequately represented by
gaussian, exponential, power-law or Edgeworth parametrisations, more elaborate
ones such as Levy and an exponential with a cross term do better. A two-scale
model using a hard cut to separate small and large scales may indicate a core
that is more prolate than the halo. Consideration not only of the interference
peak at small (q_L,q_T), but also of the shape of the correlation distribution
at intermediate momentum differences is crucial to understanding the data.
