[WARNING] This document format requires a nonempty title element.

If you are using pandoc as a document converter from markdown to html, you may have this warning message while using the -s (–standalone) option.

[WARNING] This document format requires a nonempty title element.
Please specify either ‘title’ or ‘pagetitle’ in the metadata.

For more details about adding metadata information to your pandoc command line : https://pandoc.org/MANUAL.html#option–metadata
For example, if you want to produce an HTML file from a markdown file, the -s option uses a default template that only sets the header and the footer.
No html-based title is generated unless you explicitly request it using the -M option that sets the title metadata info.

pandoc -s -f gfm -t html -M title:Test -o test.html test.md

More info on the -s / –standalone option

Unicode primer

Understanding and manipulating character sets encoding can not be underestimated.

Here are a few interesting Unicode primers found on the Internet :