How to put side notes in available whitespace, not just in margins

Question

I'm creating a document that shows a template of a documentation standard. I'd like to put in some miscellaneous notes for the template placeholders. Something like

[date1]   [COMMENT: Please use only dates obtained from
[date2]   the Center for Dates.]
[date3]

Since the date list will have lots of white space to its right, I'd like the comment to appear there. It's closer to home and conserves space. The closest I found to what I want is \marginpar{} but it doesn't quite do the trick.

How can I do this in LaTeX?

Answer 1

The difficulty with this layout, is that the dates are printed using a different grid from those of the comments, i.e., it makes a tabular environment an unsuitable way to typeset such a layout. In a way, the comments are typeset as "sideways-footnotes"!

To make it convenient for the author to enter the lines, we provide a user command as:

\adddate{date..}{Please ....}

We create a list to hold all the data. We then iterate through the list and typeset using two minipages. Adding a bit more salt and pepper and some LaTeX kernel black magic commands we get the minimal below:

\documentclass{article}
\makeatletter
\def\listone{}
\def\adddate#1#2{
   \ifx\@empty\listone
       \g@addto@macro{\listone}{#1}
       \else \g@addto@macro{\listone}{,#1}
   \fi
   \expandafter\def\csname#1\endcsname{\footnotesize #2}
}

\parindent0pt
\begin{document}
% add some data 
\adddate{date1}{1 Please use only dates obtained from the Center for Dates.}
\adddate{date2}{2 Please use original dates.}
\adddate{date3}{3 Please use original dates.}
% print the data
% define a macro for this for convenience
% if you want
\begin{minipage}[t]{2.5cm}
\@for\next:=\listone\do{%
    \next \par
}
\end{minipage}
\begin{minipage}[t]{3cm}
\@for\next:=\listone\do{%
    \@nameuse\next \par
}
\end{minipage}
\end{document}

You can add an additional macro to hold the code for the loops, if you are going to use such code extensively.