Inconsistent heading levels in NVDA Element List

[sdcock]

Brief summary

NVDA reads headers on the web with the correct heading level (e.g. level 1 for <h1> tags). However, in the element list, headings start at level 0, meaning header tags are displayed to have lower heading levels than they should have. E.g. <h1> tags are shown as level 0, <h2> tags are shown as level 1, etc.

Steps to reproduce

1. Start NVDA
2. Open a web page in a browser with headers in it
3. Open developer tools and navigate to a header tag
4. Open the element list
5. Notice the difference in heading levels in the element list versus in developer tools and NVDA

Actual behavior

The element list reads headers with their heading level one lower than what they should be.

Expected behavior

The element list reads header levels starting from 1, not from 0.

NVDA logs, crash dumps and other attachments

No response

NVDA type

installed copy

NVDA version

2025.3.2.53588

Have you tried any other versions of NVDA? If so, please report their behaviors.

No

Windows version

Windows 11 Pro Version 24H2 Build 26100.7171

Name and version of other software in use when reproducing the issue

Mozilla Firefox 64-bit version 145.0.2

Other information about your system

No response

Does the issue still occur after restarting your computer?

I have restarted my computer and the issue still occurs

If NVDA add-ons are disabled, is your problem still occurring?

I have restarted NVDA with add-ons disabled and the issue still occurs

Does the issue still occur after you run the COM Registration Fixing Tool in NVDA's tools menu?

I have run the COM Registration Fixing Tool and the issue still occurs

[seanbudd]

The level mentioned here is the tree view level, rather than the heading level. This is intended behaviour, however we can agree that 0-indexing rather than starting with 1 can be confusing for tree view levels as well. We would like more feedback on whether we should start tree view levels at 0 or 1