Using Underlying Styles with Custom Styles

When creating custom styles, you can specify an Underlying Style that tells OneNote and Onetastic which built-in heading level your custom style represents. This is particularly important when using macros like TOC in Current Page that rely on heading styles to build a table of contents.

The Problem: Custom Styles Are Invisible to TOC Macros

By default, when you create a custom style without specifying an underlying style, it is treated as Normal (regular paragraph text). Macros like TOC in Current Page only look for OneNote's built-in heading styles (Heading 1, Heading 2, Heading 3, etc.). This means that your custom heading styles will not appear in the table of contents at all, even if they look like headings.

The Solution: Set Underlying Styles

To make your custom heading styles work with TOC and other heading-aware macros, you need to set the Underlying Style to the appropriate heading level. This tells Onetastic: "This custom style should be treated as a Heading 1 (or 2, or 3, etc.) for macro purposes."

How to Set Underlying Styles

When creating or modifying a custom style, you can specify which built-in OneNote style it represents:

1. Open the Custom Styles dialog by clicking Custom Styles > Save Selection as Custom Style (for new styles) or Custom Styles > Manage Custom Styles (for existing styles)
2. In the Custom Styles dialog, locate the Underlying Style dropdown in the left panel
3. Select the appropriate heading level that matches the logical hierarchy of your custom style:
   • Heading 1 - For top-level headings (main sections)
   • Heading 2 - For second-level headings (subsections)
   • Heading 3 - For third-level headings (sub-subsections)
   • Heading 4, 5, 6 - For deeper nesting levels
   • Normal - For regular paragraph text (default)
4. Complete your custom style configuration and click Save

Example: Creating Custom Heading Styles That Work with TOC

Let's say you want to create three custom heading styles with different colors and fonts that will appear properly in your table of contents:

1. Custom Heading 1 - Dark blue, 18pt, bold
   • Set Underlying Style to Heading 1
2. Custom Heading 2 - Medium blue, 14pt, bold
   • Set Underlying Style to Heading 2
3. Custom Heading 3 - Light blue, 12pt, italic
   • Set Underlying Style to Heading 3

With these underlying styles set correctly, when you run TOC in Current Page:

• Your custom headings will appear in the table of contents
• They will be properly indented according to their hierarchy level (Heading 1 = no indent, Heading 2 = one level indent, Heading 3 = two levels indent)

Tips and Best Practices

• CRITICAL - Always reapply after modifying: If you modify an existing custom style to add or change its underlying style, you must reapply the custom style to every paragraph that uses it. Modifying a style does not automatically update text that was previously formatted with that style. Users often forget this step and wonder why their headings still don't appear in TOC!
• If your custom headings don't appear in TOC: The most common reason is that their underlying style is set to "Normal" (the default). Change it to Heading 1, 2, 3, etc. to make them visible to TOC macros. Remember: after changing the style definition, you must reapply it to all affected paragraphs.
• Be consistent: If you create multiple custom heading styles, make sure to set their underlying styles to reflect the logical hierarchy you want to maintain
• Update existing styles: If you already have custom heading styles without underlying styles set, you can modify them to add the appropriate underlying style
• Test with TOC: After setting underlying styles, and reapplying the styles, run the TOC in Current Page macro to verify that your headings now appear and are properly indented
• You don't need underlying styles for non-heading styles: Only set underlying styles if you want your custom style to be treated as a heading by macros. Regular text styles should remain as "Normal"