# Electrical Engineering needs a Markdown solution for overline

The introduction of tables was a great addition to the Electrical Engineering substack, since I often want to quote tables from electronic component datasheets. An actual table is far more functional than a screenshot of a table even if it often takes up more room.

But now that I start converting screenshots into real tables I see a pressing need to render text with overline which is used to denote that a signal is inverted. It is very common when discussing topics in electrical engineering, and I have not found a way to do it on Stack Exchange.

Here is an example of what I want to achieve. Note the bar over the text CS/LD in the first column:

According to the answers to the question Is there a way to overline text in (GitHub flavoured) Markdown? there could be two or three ways to solve this, but I've found that neither works well.

### text-decoration:overline

Quoted: <span style="text-decoration:overline">RESET</span> Rendered: RESET

This would be the preferred method, but it seems to be filtered out by the renderer and I can't see why. The quote from We're switching to CommonMark seems to be false:

I’ve prepared a feature that will swap out our current, home-grown Markdown renderers with well-tested open-source implementations that adhere to the CommonMark specification. For the curious: this means we’re replacing PageDown with markdown-it on the client side and MarkdownSharp with markdig on the server side.

markdig's output on Babelmark renders this correctly. So does the CommonMark reference implementation.

markdown-it strips HTML tags by default, but the output on Babelmark does not look like the preview here.

### Unicode Combining Overline

Unicode lets you add a Combining Overline to each character, but this is not optimal:

### MathJax

Where MathJax is enabled you can use something like $\rm\overline{RESET}$. This changes the font, adds a lot of unnecessary complexity, and only works on a few select sites.

• The SE team does also check per-site metas for feature requests and bug reports, not only this site, so if this is truly specific to EE.SE you should post on their meta. Dec 12, 2020 at 0:40
• @SonictheK-DayHedgehog I considered that but decided to post here for two reasons. 1. Every time someone asks about a feature on the EE meta the answer is always "Rendering is site-wide so we can't change anything", and 2. This would be useful for any site dealing with electronics, logic, and mathematics, so I thought I'd start here.
– pipe
Dec 12, 2020 at 0:57
• Dec 12, 2020 at 1:38
• There's over 500 overline questions already, and as you can see, MathJax tables are trivial to compose and easy to read; example at the end shows it adds three lines to the data.
– Rob
Dec 12, 2020 at 1:52
• O̅v̅e̅r̅l̅i̅n̅e̅ ̅e̅x̅a̅m̅p̅l̅e̅ - generated by: fsymbols.com/generators/overline - there's more than one site that offers that service.
– Rob
Dec 12, 2020 at 1:59
• @Rob I covered the MathJax hack and the unicode-version in the actual question. I also mentioned how broken it is. What is the point of your comment? It doesn't render correctly in many browsers.
– pipe
Dec 12, 2020 at 2:01
• pipe, the "point" of my comment is: many people already have worked around the problem. --- Using MathJax correctly doesn't produce an unusable font, and it can easily be stored in an HTML comment on non-MathJax sites. --- I suggest that you offer a more convincing reason to assign the time and expense of having a developer perfect what you perceive as less than perfect results; that are already accepted by 1000's of people. Stack Exchange requires strong reason to spend the money. You are welcome to leave your Feature Request as-is, and reject offered advice; it's common practice.
– Rob
Dec 12, 2020 at 2:34
• Eh. Its in the spec, there might be sites other than EE that could use it. I'd totally see myself status-reviewing this if I knew its something the devs were working on. There is no good reason to throw cold water on this feature request.
– Journeyman Geek Mod
Dec 12, 2020 at 2:53
• @JourneymanGeek I don't think it's in the spec. I don't think the spec covers much styling at all - markdown is mostly converting to HTML; CSS doesn't really enter the equation. The effect wanted here, though, is a question of styling. The reason it works for the implementations mentioned here is the CSS class involved having that effect.
– muru
Dec 12, 2020 at 4:19
• Also related meta post: What HTML tags are allowed on Stack Exchange sites?: because the <span> tag is not supported, so while it might be rendered on the client, it will be stripped on the server anyway. Dec 12, 2020 at 7:32