How to remove dot in tabular rule when using hhline?

Question

I have a large table which represents a calendar (produced by yplan) and I'm trying to typeset the cell in the top left corner without any rules at all. I've all but solved the rules, but I'm left with a small dot in the bottom right corner of the cell. I'm using hhrule for my horizontal rules as it is suggested by the colortbl manual which I am using to fill cells. (Colour not represented in minimal example below).

This is a minimal example of what my problem is:

\documentclass{article}
\usepackage{hhline}

\begin{document}
\begin{tabular}{|c||p{2.5cm}|}
\hhline{~|-}
\multicolumn{1}{c|}{} & \multicolumn{1}{c|}{\textbf{JANUARY}} \\[0.75ex]
\hhline{-::=}
\textbf{Su} & \\[0.75ex]
\end{tabular}
\end{document}

Which produces output that looks like (note the small dot):

I've tried countless combinations of rule options and just can't get it right. Can anyone help?

Answer 1

this adds a ; which is like : but different.

\documentclass{article}
\usepackage{hhline,colortbl}

\makeatletter
\AtBeginDocument{%
\def\HH@loop{%
  \ifx\@tempb`\def\next##1{\the\toks@\cr}\else\let\next\HH@let
  \ifx\@tempb|\if@tempswa
          \ifx\CT@drsc@\relax
           \HH@add{\hskip\doublerulesep}%
          \else
           \HH@add{{\CT@drsc@\vrule\@width\doublerulesep}}%
           \fi
          \fi\@tempswatrue
          \HH@add{{\CT@arc@\vline}}\else
  \ifx\@tempb:\if@tempswa
          \ifx\CT@drsc@\relax
           \HH@add{\hskip\doublerulesep}%
          \else
           \HH@add{{\CT@drsc@\vrule\@width\doublerulesep}}%
           \fi
              \fi\@tempswatrue
      \HH@add{\@tempc\HH@box\arrayrulewidth\arrayrulewidth\@tempc}\else
  \ifx\@tempb;\if@tempswa
          \ifx\CT@drsc@\relax
           \HH@add{\hskip\doublerulesep}%
          \else
           \HH@add{{\CT@drsc@\vrule\@width\doublerulesep}}%
           \fi
              \fi\@tempswatrue
      \HH@add{\@tempc\HH@box\z@\arrayrulewidth\@tempc}\else
  \ifx\@tempb##\if@tempswa\HH@add{\hskip\doublerulesep}\fi\@tempswatrue
         \HH@add{{\CT@arc@\vline\copy\@ne\@tempc\vline}}\else
  \ifx\@tempb~\@tempswafalse
           \if@firstamp\@firstampfalse\else\HH@add{&\omit}\fi
              \ifx\CT@drsc@\relax
                \HH@add{\hfil}\else
                 \HH@add{{%
                   \CT@drsc@\leaders\hrule\@height\HH@height\hfil}}%
               \fi
                 \else
  \ifx\@tempb-\@tempswafalse
           \gdef\HH@height{\arrayrulewidth}%
           \if@firstamp\@firstampfalse\else\HH@add{&\omit}\fi
              \HH@add{{%
                \CT@arc@\leaders\hrule\@height\arrayrulewidth\hfil}}%
                           \else
  \ifx\@tempb=\@tempswafalse
       \gdef\HH@height{\dimen\thr@@}%
       \if@firstamp\@firstampfalse\else\HH@add{&\omit}\fi
       \HH@add
          {\rlap{\copy\@ne}\leaders\copy\@ne\hfil\llap{\copy\@ne}}\else
  \ifx\@tempb t\HH@add{%
    \def\HH@height{\dimen\thr@@}%
    \HH@box\doublerulesep\z@}\@tempswafalse\else
  \ifx\@tempb b\HH@add{%
    \def\HH@height{\dimen\thr@@}%
    \HH@box\z@\doublerulesep}\@tempswafalse\else
  \ifx\@tempb>\def\next##1##2{%
     \HH@add{%
      {\baselineskip\p@\relax
       ##2%
      \global\setbox\@ne\HH@box\doublerulesep\doublerulesep}}%
       \HH@let!}\else
  \PackageWarning{hhline}%
      {\meaning\@tempb\space ignored in \noexpand\hhline argument%
       \MessageBreak}%
  \fi\fi\fi\fi\fi\fi\fi\fi\fi\fi\fi
  \next}
}
\makeatother
\begin{document}
\begin{tabular}{|c||p{2.5cm}|}
\hhline{~|-}
\multicolumn{1}{c|}{} & \multicolumn{1}{c|}{\textbf{JANUARY}} \\[0.75ex]
\hhline{-;:=}
\textbf{Su} & \\[0.75ex]
\end{tabular}
\end{document}

Answer 2

The probelm comes from a\hhline which mixes simple and doublerule. A solution consists in making two simple \hhmines with a vertical space in-between:

\documentclass{article}
\usepackage{hhline}

\begin{document}

\begin{tabular}{|c||p{2.5cm}|}
\hhline{~|-}
\multicolumn{1}{c|}{}& {\textbf{JANUARY}} \\[0.75ex]
\hhline{~|-}\noalign{\vspace*{\doublerulesep}}
\hhline{-||-}
\textbf{Su} & \\[0.75ex]
\end{tabular}

\end{document}