# Why does tab completion only work for some letters?

**URL:** <https://discourse.julialang.org/t/why-does-tab-completion-only-work-for-some-letters/56971>\
**Category:** General Usage\
**Created:** [March 11, 2021, 7:45pm UTC](https://discourse.julialang.org/t/why-does-tab-completion-only-work-for-some-letters/56971 "2021-03-11T19:45:01Z")\
**Posts on this page:** 7\
**Page:** 1

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**Author:** ![nickeubank](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/nickeubank/32/3878_2.png) [@nickeubank](https://discourse.julialang.org/u/nickeubank)\
**Post date:** [March 11, 2021, 7:45pm UTC](https://discourse.julialang.org/t/why-does-tab-completion-only-work-for-some-letters/56971/1 "2021-03-11T19:45:01Z")

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I’ve noticed only some letters are supported for latex subscripts in variable names.

e.g. `\sigma <tab> \_h <tab>` renders as σₕ, but `\sigma <tab> \_f <tab>` just flashes.

Is there a reason for this and/or a workaround? Just modeling code from a paper that subscripts with F, so curious.

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**Author:** ![WschW](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/wschw/32/6575_2.png) [@WschW](https://discourse.julialang.org/u/WschW)\
**Post date:** [March 11, 2021, 7:50pm UTC](https://discourse.julialang.org/t/why-does-tab-completion-only-work-for-some-letters/56971/2 "2021-03-11T19:50:52Z")

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Julia uses unicode to represent characters in text. Unicode does not support subscripts for all letters, for instance there is no y subscript. Likely there is also no f subscript as well.

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**Author:** ![Palli](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/palli/32/3380_2.png) [@Palli](https://discourse.julialang.org/u/Palli)\
**Post date:** [March 12, 2021, 9:26am UTC](https://discourse.julialang.org/t/why-does-tab-completion-only-work-for-some-letters/56971/3 "2021-03-12T09:26:55Z")

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As stated this is for Unicode, not specifically subscripts, and Unicode only chose to have subscripts for some letters, e.g. not f…:

> **[Unicode subscripts and superscripts](https://en.wikipedia.org/wiki/Unicode_subscripts_and_superscripts#Latin_and_Greek_tables)**
>
> Unicode has subscripted and superscripted versions of a number of characters including a full set of Arabic numerals. These characters allow any polynomial, chemical and certain other equations to be represented in plain text without using any form of markup like HTML or TeX.
> The World Wide Web Consortium and the Unicode Consortium have made recommendations on the choice between using markup and using superscript and subscript characters:
> When used in mathematical context (MathML) it is recomm...

Maybe LaTeX allows more, as it’s for typesetting, Julia isn’t really, nor most programming languages. The argument for Unicode is you could use such a system with, and they don’t want to support subscripting just any letter (e.g. Chinese). Why they chose that subset is another story.

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**Author:** ![MarcMush](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/marcmush/32/18006_2.png) [@MarcMush](https://discourse.julialang.org/u/MarcMush)\
**Post date:** [March 12, 2021, 9:52am UTC](https://discourse.julialang.org/t/why-does-tab-completion-only-work-for-some-letters/56971/4 "2021-03-12T09:52:36Z")

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(definitely offtopic)  
I feel like there should be a subscript and superscript modifier, like it’s done for emoji skin color.  
That way, any character could be raised or lowered without taking space in the Unicode space

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**Author:** ![Tamas\_Papp](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/tamas_papp/32/25949_2.png) [@Tamas\_Papp](https://discourse.julialang.org/u/Tamas_Papp)\
**Post date:** [March 12, 2021, 10:10am UTC](https://discourse.julialang.org/t/why-does-tab-completion-only-work-for-some-letters/56971/5 "2021-03-12T10:10:09Z")

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> [@MarcMush](#):
>
> I feel like there should be a subscript and superscript modifier

I think it is cleaner to separate plain text and markup languages.

Also, keep in mind that super- and subscripts may not be very legible at all screen sizes and resolutions. Personally, after some very enthusiastic initial experimentation with stuff like `xₐ₁`, I decided not to use them in my own code.

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**Author:** ![lferrant](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/lferrant/32/22751_2.png) [@lferrant](https://discourse.julialang.org/u/lferrant)\
**Post date:** [March 12, 2021, 10:15am UTC](https://discourse.julialang.org/t/why-does-tab-completion-only-work-for-some-letters/56971/6 "2021-03-12T10:15:01Z")

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there was a discussion in slack a few months back about making a proposal to the unicode consortium to add more subscripts superscripts characters.

The draft of the proposal seems to be here:

> **[GitHub - stevengj/subsuper-proposal: Draft proposal for additional...](https://github.com/stevengj/subsuper-proposal)**
>
> Draft proposal for additional sub/superscript characters in Unicode - GitHub - stevengj/subsuper-proposal: Draft proposal for additional sub/superscript characters in Unicode

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**Author:** ![nickeubank](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/nickeubank/32/3878_2.png) [@nickeubank](https://discourse.julialang.org/u/nickeubank)\
**Post date:** [March 12, 2021, 12:46pm UTC](https://discourse.julialang.org/t/why-does-tab-completion-only-work-for-some-letters/56971/7 "2021-03-12T12:46:48Z")

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I had no idea! Since I was writing latex shorthands I’d assumed I could do anything I could do in Latex. Thanks for the explanation!