61.2 Lists (Rosters

without the par below we get an extra <P> when \nextii@ applies in \roster

<..roster in amsppt.sty..>
 \let\:roster=\roster
 \def\roster{\IgnorePar
    \let\roster:par=\par
    \def\par{\let\par=\roster:par \par
       \def\:tempa{\ifx \:temp\par@  \IgnorePar\leavevmode\IgnorePar\fi}%
       \futurelet\:temp\:tempa}%
    \:roster   \let\ams:tem=\item
    \def\item{\IgnorePar\EnditemitemList \ams:tem}%
    \a:roster}
 \pend:def\endroster{\EnditemitemList\b:roster}
 -_-_-

<..roster in amsppt.sty..>+
 \pend:def\itembox@{\ifx \EndPicture\:UnDef
    \a:itembox@ \therosteritem@ \b:itembox@ \expandafter\:gobbleII\fi}
 -_-_-

<..roster in amsppt.sty..>+
 \NewConfigure{roster}[4]{\def\:temp{#1#2#3#4}\ifx \:temp\empty
    \else \def\a:roster{\ii:conf#1}\def\b:roster{#2}%
          \def\a:itembox@{#3}\def\b:itembox@{#4}\fi
    \long\def\:temp##1##2##3##4{\def\:temp{##1##2##3##4}\ifx \:temp\empty
       \else
       \def\ii:conf{\Configure{itemitem}{##1}{##2}{##3}{##4}}\fi}\:temp}
 -_-_-

Configure \item and/or \itemitem, provided that at least one of the pars is not empty

<..roster in amsppt.sty..>+
 <.itemitem from tex.>
 -_-_-

The following is from TeX4ht2.

<..itemitem from tex..>
 \ifx \EnditemitemList\:UnDef
    <.plain+ itemitem list.>
 \fi
 -_-_-