The microtype package

THE LETTERSPACING ILLUSTRATION: Macros 218The bounding box.9017 \mts@layer{stuff}{%9018 \node[draw=thegrey,9019 fill=theshade,9020 outer sep=\lsrule,9021 anchor=base,9022 font=\lsfont]{\phantom{#1}};9023 }The letter.9024 \node[anchor=base,font=\lsfont](#1){#1};Two auxiliary coordinates.9025 \path (#1.south west) ++(+.5\lsrule,-.5\lsrule) coordinate (#1L);9026 \path (#1.base east) ++(-.5\lsrule,-\lsdepth) coordinate (#1R);9027 \mts@layer{stuff}{%Now draw the normal character width,9028 \draw[color=thered!75,9029 fill=thered!30,9030 outer sep=\lsrule]9031 (#1L) rectangle (#1R);9032 \ifdim\lsamount>0pt9033 \path (#1.base east) ++(+.5\lsamount,-6pt) coordinate (#1 _ ls);9034 \path (#1R) ++(\lsamount+\lsrule,+\lsdepth) coordinate (#1E);and the letter space.9035 \draw[color=thered,9036 fill=thered!50,9037 outer sep=\lsrule]9038 (#1R) ++(+\lsrule,+0pt) rectangle (#1E);9039 \fi9040 }9041 \end{tikzpicture}%9042 \ignorespaces9043 }Draw the interword space.9044 \def\lssp#1#2#3#4{%9045 \mts@layer{stuff}{%9046 \begin{tikzpicture}[remember picture,line width=\lsrule,inner sep=0pt]9047 \tikzstyle{every draw}=[anchor=bottom]9048 \coordinate(#1space) at (#2/2,\lsdepth/2);9049 \coordinate(#1stretch) at (#2+#3/2,+0pt);9050 \coordinate(#1shrink) at (#2-#4/2,+0pt);9051 \draw[color=thegreen,fill=thegreen!50,use as bounding box]9052 (0,0) rectangle ++(+#2,+\lsdepth);9053 \draw[color=thegreen,fill=thegreen!30]9054 (+#2,-\lsrule) rectangle ++(+#3,-4pt+\lsrule);9055 \draw[color=thegreen,fill=thegreen!50]9056 (+#2,-\lsrule) rectangle ++(-#4,-4pt+\lsrule);9057 \draw[->,line width=0.3pt,shorten ,line width=0.3pt,shorten