HTML Guides for unicode private use area

Private Use Area (PUA) characters are reserved ranges in Unicode whose interpretation is not specified by any encoding standard. Their meaning is determined entirely by private agreement between cooperating parties—such as a font vendor and its users. This means that a PUA character that renders as a custom icon in one font may appear as a blank square, a question mark, or a completely different glyph when that specific font is unavailable.

This warning commonly appears when using icon fonts like older versions of Font Awesome, Material Icons, or custom symbol fonts. These fonts map their icons to PUA code points. While this approach works visually when the font loads correctly, it creates several problems:

• Accessibility: Screen readers cannot interpret PUA characters meaningfully. A visually impaired user may hear nothing, hear “private use area character,” or hear an unrelated description depending on their assistive technology.
• Portability: If the associated font fails to load (due to network issues, content security policies, or user preferences), the characters become meaningless boxes or blank spaces.
• Interoperability: Copy-pasting text containing PUA characters into another application, email client, or document will likely produce garbled or missing content since the receiving system won’t know how to interpret those code points.
• Standards compliance: The W3C and Unicode Consortium both recommend against using PUA characters in publicly exchanged documents for exactly these reasons.

Sometimes PUA characters sneak into your HTML unintentionally—through copy-pasting from word processors, PDFs, or design tools that use custom encodings. Other times, they are inserted deliberately via CSS content properties or HTML entities by icon font libraries.

To fix this, identify where the PUA characters appear and replace them with standard alternatives. Use inline SVG for icons, standard Unicode symbols where appropriate (e.g., ✓ U+2713 instead of a PUA checkmark), or CSS background images. If you must use an icon font, hide the PUA character from assistive technology using aria-hidden="true" and provide an accessible label separately.

Examples

Problematic: PUA character used directly in HTML

<p>Status: </p>

The character ` (U+E001) is a PUA code point. Without the specific icon font loaded, this renders as a missing glyph. ### Fixed: Using inline SVG with accessible label ```html <p> Status: <svg aria-hidden="true" width="16" height="16" viewBox="0 0 16 16"> <path d="M6 10.8L2.5 7.3 1.1 8.7 6 13.6 14.9 4.7 13.5 3.3z"/> </svg> <span>Complete</span> </p> ``` ### Problematic: Icon font via CSS content property ```html <style> .icon-check::before { font-family: "MyIcons"; content: "\e001"; /* PUA character */ } </style> <span class="icon-check"></span> ``` ### Fixed: Icon font with accessibility safeguards If you must continue using an icon font, hide the PUA character from assistive technology and provide an accessible alternative: ```html <style> .icon-check::before { font-family: "MyIcons"; content: "\e001"; } </style> <span class="icon-check" aria-hidden="true"></span> <span class="sr-only">Checkmark</span> ``` Note that this approach still triggers the validator warning if the PUA character is detectable in the markup. The most robust fix is to avoid PUA characters entirely. ### Fixed: Using a standard Unicode character ```html <p>Status: ✓ Complete</p> ``` The character✓` (U+2713, CHECK MARK) is a standard Unicode character that is universally understood and renders consistently across platforms. ### Problematic: PUA character from copy-paste html <p>Click here to download</p> Invisible or unexpected PUA characters sometimes hide in text pasted from external sources. Inspect your source code carefully—many code editors can highlight non-ASCII characters or reveal their code points. ### Fixed: Cleaned-up text html <p>Click here to download</p> If you’ve audited your document and determined that the PUA characters are intentional and rendering correctly in your target environments, you may choose to accept this warning. However, for publicly accessible web pages, replacing PUA characters with standard alternatives is always the safer and more accessible choice.