\begin{theindex}

  \item columnseprule=\verb
    \subitem *+\columnseprule+, \usage{2}

  \indexspace

  \item multicolbaselineskip=\verb
    \subitem *+\multicolbaselineskip+, \usage{2}
  \item multicolsep=\verb
    \subitem *+\multicolsep+, \usage{2}

  \indexspace

  \item postmulticols=\verb
    \subitem *+\postmulticols+, \usage{2}
  \item premulticols=\verb
    \subitem *+\premulticols+, \usage{2}

\end{theindex}