The microtype package

THE LETTERSPACING ILLUSTRATION: Macros 2199071 \immediate\pdfobj{>}9072 \expandafter\xdef\csname mts@#1\endcsname{\the\pdflastobj\space 0 R }9073 \xdef\mt@objects{\mt@objects\csname mts@#1\endcsname}9074 \xdef\mt@order{\mt@order\csname mts@#1\endcsname}9075 \xdef\mts@resources{\mts@resources/#1 \csname mts@#1\endcsname}}9076 \mts@register{stuff}9077 \mts@register{tracking}9078 \mts@register{ispace}9079 \mts@register{ospace}9080 \mts@register{istretch}9081 \mts@register{ishrink}9082 \mts@register{ostretch}9083 \mts@register{oshrink}9084 \mts@register{okern}9085 \mts@register{ligature}9086 \mts@register{ _ compatibility}9087 \xdef\mt@order{\mt@order]}Anchor point for the arrow in the code.9088 \newcommand\anchorarrow[1]{%9089 \tikz[remember picture,overlay]\node(#1 _ c){};}Add an arrow from code to image.9090 \newcommand\add@arrow[5][left]{%9091 \tikz[remember picture,overlay,bend angle=14,looseness=0.75,>=latex]{%9092 \mtsx@layer{#3}{%9093 \draw[->,thick,color=the#2](#4) to[bend #1] (#5);}}%9094 }Toggle layer.9095 \def\toggle@layer#1#2#3{%9096 \pdfstartlink9097 user{/Subtype/Link9098 /BS > /H/O9099 % /BS >9100 % /C[0.7 0.7 0.7] /H/O9101 /Contents(Click to Toggle!)9102 /A >9104 }%9105 \rlap{#2}%9106 {\fboxsep=0pt \fboxrule=0pt9107 \mtsx@layer{stuff}{%9108 \rlap{\fcolorbox{white}{white}{\vphantom{kg}\color{the#3}#2}}}%9109 \mtsx@layer{#1}{%9110 \fcolorbox{white}{the#3!50}{\vphantom{kg}\color{white}#2}}%9111 }%9112 \pdfendlink9113 }9114 \newcommand\showarrow[2][]{%9115 \ifx\relax#1\relax\def\@tempa{#2}\else\def\@tempa{#1}\fi9116 \toggle@layer{\@tempa}{{\itshape #2}}}The environment for our illustration.9117 \def\ls@sample#1{{%9118 \parskip 4pt \parindent 0pt9119 \par9120 \vskip4pt9121 {\leftskip 15pt9122 \mt@pseudo@marg{\color{theblue}Click on the image to show the kerns9123 and spacings involved. Click on emphasised words in the text below9124 to reveal the relation of image and code.}9125 \mt@layer{ _ compatibility}{%9126 \mt@place{\rlap{\hskip-\marginparwidth \color{white}%9127 \vrule width\dimexpr\hsize+\marginparwidth\relax height\mt@unvdimen}}9128 \mt@pseudo@marg{\color{thered}%9129 If you had a \acronym{PDF} viewer that understands