  We find that element abundances in energetic ions accelerated by shock waves
formed at corotating interaction regions (CIRs) mirror the abundances of the
solar wind modified by a decreasing power-law dependence on the mass-to-charge
ratio A/Q of the ions. This behavior is similar in character to the well-known
power-law dependence on A/Q of abundances in large gradual solar energetic
particles (SEP). The CIR ions reflect the pattern of A/Q, with Q values of the
source plasma temperature or freezing-in temperature of 1.0 - 1.2 MK typical of
the fast solar wind in this case. Thus the relative ion abundances in CIRs are
of the form (A/Q)**a where a is nearly always negative and evidently decreases
with distance from the shocks, which usually begin beyond 1 AU. For one unusual
historic CIR event where a ~ 0, the reverse shock wave of the CIR seems to
occur at 1 AU, and these abundances of the energetic ions become a direct proxy
for the abundances of the fast solar wind.
