Web browsing anchored the habit of associating underlined content with links. By highlighting content that is not links, there is a risk of causing unnecessary clicks. Be careful, this does not require you to emphasize your links.
Objectives
Avoid unnecessary clicks on content marked as hyperlinks.
Facilitate the identification of links.
Implementation
Do not use underscore for simple texts or elements that do not constitute links.
Control
In each file containing underlined content :
Identify underlined texts in ebook;
Controlling the nature of these contents to verify whether they are actually hyperlinks.