There are three slightly different things going on. The first line, Ｔｈｅ ｑｕｉｃｋ ｂｒｏｗｎ ｆｏｘ, originates with east-Asian character based terminals, on which ideogra

There are three slightly different things going on. The first line, Ｔｈｅ ｑｕｉｃｋ ｂｒｏｗｎ ｆｏｘ, originates with east-Asian character based terminals, on which ideographic characters occupied twice the space of alphabetic characters, and there was also a desire to have latin characters that were also double width. See https://en.wikipedia.org/wiki/Halfwidth_and_fullwidth_forms https://en.wikipedia.org/wiki/Halfwidth_and_fullwidth_forms The middle lines are included as mathematical symbols. The justification is that 𝑖 is a mathematical symbol that has its own independent meaning, which only coincidentally looks like italicized i. (I think this is silly, and naturally leads to a bloody mess as people misuse these symbols as letters, and in this case there is no backwards-compatbility excuse.) https://en.wikipedia.org/wiki/Mathematical_Alphanumeric_Symbols https://en.wikipedia.org/wiki/Mathematical_Alphanumeric_Symb... The final line, like the first, is apparently present for compatibility with pre-Unicode east-Asian character sets. https://en.wikipedia.org/wiki/Enclosed_Alphanumerics https://en.wikipedia.org/wiki/Enclosed_Alphanumerics