\begin{array}{llllllll}
 & \text{219} & \text{21A} & \text{21B} & \text{21C} & \text{21D} & \text{21E} & \text{21F} \\
\text{0} & \leftarrow & \twoheadrightarrow & \Lsh & \rightharpoonup & \Leftarrow & & \\
\text{1} & \uparrow & & \Rsh & \rightharpoondown & \Uparrow & & \\
\text{2} & \rightarrow & \leftarrowtail & & \downharpoonright & \Rightarrow & & \\
\text{3} & \downarrow & \rightarrowtail & & \downharpoonleft & \Downarrow & & \\
\text{4} & \leftrightarrow & & & \rightleftarrows & \Leftrightarrow & & \\
\text{5} & \updownarrow & & & & \Updownarrow & & \\
\text{6} & \nwarrow & \mapsto & \curvearrowleft & \leftrightarrows & & & \\
\text{7} & \nearrow & & \curvearrowright & \leftleftarrows & & & \\
\text{8} & \searrow & & & \upuparrows & & & \\
\text{9} & \swarrow & \hookleftarrow & & \rightrightarrows & & & \\
\text{A} & \nleftarrow & \hookrightarrow & \circlearrowleft & \downdownarrows & \Lleftarrow & & \\
\text{B} & \nrightarrow & \looparrowleft & \circlearrowright & \leftrightharpoons & \Rrightarrow & & \\
\text{C} & & \looparrowright & \leftharpoonup & \rightleftharpoons & & & \\
\text{D} & & \leftrightsquigarrow & \leftharpoondown & \nLeftarrow & \rightsquigarrow & & \\
\text{E} & \twoheadleftarrow & \nleftrightarrow & \upharpoonright & \nLeftrightarrow & & & \\
\text{F} & & & \upharpoonleft & \nRightarrow & & & \\
\end{array}
