Two, if you count ⊠. There was a nearly forgotten effort to define standard symbols for all the ASCII control characters — ANSI X3.32 aka ISO 2047¹ aka ECMA-17²

Two, if you count ⊠. There was a nearly forgotten effort to define standard symbols for all the ASCII control characters — ANSI X3.32 aka ISO 2047¹ aka ECMA-17². ¹ https://en.wikipedia.org/wiki/ISO_2047 https://en.wikipedia.org/wiki/ISO_2047 ² https://www.ecma-international.org/publications/files/ECMA-ST-WITHDRAWN/ECMA-17,%201st%20Edition,%20November%201968.pdf https://www.ecma-international.org/publications/files/ECMA-S...