$$\begin{array}{cccccccc}& \mathrm{\text{219}}& \mathrm{\text{21A}}& \mathrm{\text{21B}}& \mathrm{\text{21C}}& \mathrm{\text{21D}}& \mathrm{\text{21E}}& \mathrm{\text{21F}}\\ \mathrm{\text{0}}& \leftarrow & \twoheadrightarrow & \Lsh & \rightharpoonup & \Leftarrow & ⇠& ⇰\\ \mathrm{\text{1}}& \uparrow & ↡& \Rsh & \rightharpoondown & \Uparrow & ⇡& ⇱\\ \mathrm{\text{2}}& \to & \leftarrowtail & ↲& \downharpoonright & \Rightarrow & ⇢& ⇲\\ \mathrm{\text{3}}& \downarrow & \rightarrowtail & ↳& \downharpoonleft & \Downarrow & ⇣& ⇳\\ \mathrm{\text{4}}& \leftrightarrow & ↤& ↴& \rightleftarrows & \iff & ⇤& ⇴\\ \mathrm{\text{5}}& \updownarrow & ↥& ↵& ⇅& \Updownarrow & ⇥& ⇵\\ \mathrm{\text{6}}& \nwarrow & \mapsto & \curvearrowleft & \leftrightarrows & ⇖& ⇦& ⇶\\ \mathrm{\text{7}}& \nearrow & ↧& \curvearrowright & \leftleftarrows & ⇗& ⇧& ⇷\\ \mathrm{\text{8}}& \searrow & ↨& ↸& \upuparrows & ⇘& ⇨& ⇸\\ \mathrm{\text{9}}& \swarrow & \hookleftarrow & ↹& \rightrightarrows & ⇙& ⇩& ⇹\\ \mathrm{\text{A}}& \nleftarrow & \hookrightarrow & \circlearrowleft & \downdownarrows & \Lleftarrow & ⇪& ⇺\\ \mathrm{\text{B}}& \nrightarrow & \looparrowleft & \circlearrowright & \leftrightharpoons & \Rrightarrow & ⇫& ⇻\\ \mathrm{\text{C}}& ↜& \looparrowright & \leftharpoonup & \rightleftharpoons & ⇜& ⇬& ⇼\\ \mathrm{\text{D}}& \rightsquigarrow & \leftrightsquigarrow & \leftharpoondown & \nLeftarrow & ⇝& ⇭& ⇽\\ \mathrm{\text{E}}& \twoheadleftarrow & \nleftrightarrow & \upharpoonright & \nLeftrightarrow & ⇞& ⇮& ⇾\\ \mathrm{\text{F}}& ↟& ↯& \upharpoonleft & \nRightarrow & ⇟& ⇯& ⇿\end{array}$$