Global correlations of unique parity structures in odd-A nuclei

All known unique parity structures in precollective odd-A nuclei (having cores with E(41+)E(21+) < 2.0) are shown to behave similarly to the yrast quasibands in the neighboring even-even nuclei. This is interpreted in terms of a pair addition mode. With previous results on collective nuclei, this gives a tripartite classification of the evolution of the unique parity quasibands in odd-A nuclei. A simple index for signature splitting is also developed which avoids the need for complex analysis of Routhian structures.