Question: -- in BibTeX URLs is converted to %E2%80%93

[TomoakiChen]

I'm using Quarkdown 2.6.1 with a BibTeX bibliography.

I have a URL in a .bib entry that contains two consecutive hyphens (--) as part of the URL path:

@misc{737d91,
  author = {FasterCapital Team},
  title  = {Brand Story: How to Tell Your Brand Story and Connect with Your Audience on an Emotional Level},
  url    = {https://fastercapital.com/content/Brand-Story--How-to-Tell-Your-Brand-Story-and-Connect-with-Your-Audience-on-an-Emotional-Level.html},
  year   = {2026}
}

However, when Quarkdown generates the bibliography, the resulting URL contains an en dash instead of the two hyphens, which is then percent-encoded:

Brand-Story%E2%80%93How-to-Tell...

%E2%80%93 is the UTF-8 percent-encoded representation of the Unicode en dash (–).

Expected behavior

Since the two hyphens are part of the actual URL, I would expect the generated link to preserve them:

https://fastercapital.com/content/Brand-Story--How-to-Tell-...

rather than:

https://fastercapital.com/content/Brand-Story%E2%80%93How-to-Tell-...

What I tried

I also tried escaping the hyphens in several ways:

url = {https://fastercapital.com/content/Brand-Story{--}How-to-Tell-...}

url = {https://fastercapital.com/content/Brand-Story\--How-to-Tell-...}

url = {https://fastercapital.com/content/Brand-Story\-\-How-to-Tell-...}

url = {https://fastercapital.com/content/Brand-Story-\-How-to-Tell-...}

The resulting URLs were different in each case:

• -- and {--} were converted to an en dash (–), which was then percent-encoded as %E2%80%93.
• \-- resulted in a single -.
• \-\- resulted in both hyphens being removed.
• -\- resulted in a single -.

The generated link is therefore not usable: clicking it from the generated PDF results in a 404 Not Found, because the actual website URL contains two ASCII hyphens (--).

I also checked the link in Quarkdown's Preview HTML. Using the browser's Copy Clean Link still produced the URL containing %E2%80%93.

This makes me suspect that the hyphens are being interpreted or transformed somewhere during the bibliography processing stage, rather than being simply a URL encoding issue.

Question

Is this expected behavior when processing URLs in a BibTeX bibliography, or could this be an issue in the bibliography/URL processing pipeline?

In particular, could the -- in the URL be interpreted as an en dash before the URL is encoded?

Or am I missing something about how URLs containing consecutive hyphens should be written or escaped in BibTeX for Quarkdown?

Thanks!

[iamgio]

Seems to be a bug in the underlying - external - BibTeX parser. I'm investigating

[iamgio]

I've opened michel-kraemer/citeproc-java#355. In the meantime, {-}{-} and -{}- are valid workarounds. Thanks for reporting :)

[TomoakiChen]

Thanks for looking into this and for opening the citeproc-java issue!

I suspected it might be related to citeproc-java, but wasn't sure, so it's helpful to know where the issue comes from. I tested both {-}{-} and -{}-, and they work as expected. Thanks for the workaround!