Can I get straight underlines for subscripts?

When I underline words that include subscript characters, the underline gets chopped up:

Is there a way to get one straight underline for the whole word?

There are two possibilities, one is a workaround, the other a “proper” solution that involves some extra work with character styles.

The workaround is to use a border instead of underline: select the text → right click → Character → Border tab.

The second possibility is to use an OpenType font that support real subscripts through the sinf or subs OpenType substitution.

I describe how to use OpenType in LibreOffice in my book.


My favorite font is Lato – it should qualify as OpenType, right? Underlines are still interrupted though, and I understand that’s because my subscripts aren’t “real” subscripts.

So how do I make them real?

“OpenType” refers to two things: a file format and a smart font technology. I don’t have Lato on my system so I cannot tell you if it has the sinf font feature. On my example I used Libertinus Serif. For the last line, a character style was used with an “extended font name” to activate the feature, something like

Libertinus Serif:sinf

OpenType support is a complex topic, but quite powerful. Just check the book I linked above :wink:

I did look at your book but got intimidated when I learned that there is a difference between “subscript” and “scientific inferiors…”

I can get sinf to work with Libertinus. Vollkorn takes subs but not sinf, and Lato does neither.

Anyway: For the time being I’ll keep clicking Subscript in the toolbar. I’ll leave the subs and sinf to the experts and accept the broken underlines.


Lato v2.015 has both sinf and subs although it does use the same replacements for both.
Applying sinf and then underline results in the last example above (labeled OpenType).
The character border example above could easily be done with a character style.
Assign that character style to Control+0 for example and it would be very quick and easy to apply.

My workaround is to use a specific character style with bottom border. There are advantages to this:

  • it works with any font
  • you can tune the distance text-to-underline, line width and colour to you liking

To show the community your question has been answered, click the ✓ next to the correct answer, and “upvote” by clicking on the ^ arrow of any helpful answers. These are the mechanisms for communicating the quality of the Q&A on this site. Thanks!