  Excitation energies, oscillator strengths, and transition rates are
calculated for (5d2+5d6s+6s2)--(5d6p+5d5f+6s6p) electric dipole transitions in
Yb-like ions with nuclear charges Z ranging from 72 to 100. Relativistic
many-body perturbation theory (RMBPT), including the retarded Breit
interaction, is used to evaluate retarded E1 matrix elements in length and
velocity forms. The calculations start from a [Xe]4f14 core Dirac-Fock
potential. First-order RMBPT is used to obtain intermediate coupling
coefficients, and second-order RMBPT is used to determine matrix elements. A
detailed discussion of the various contributions to energy levels and dipole
matrix elements is given for ytterbium like rhenium, Z=75. The resulting
transition energies are compared with experimental values and with results from
other recent calculations. Trends of excitation energies, line strengths,
oscillator strengths, and transition rates as functions of nuclear charge Z are
shown graphically for selected states and transitions.
  These calculations are presented as a theoretical benchmark for comparison
with experiment and theory.
