> ## Documentation Index
> Fetch the complete documentation index at: https://docs.isometric.com/llms.txt
> Use this file to discover all available pages before exploring further.

# PDD quality best practice FAQs

> What sub-requirements are and why every one must be addressed, and why evidence attachments should come with a written explanation, to speed up the Isometric pre-screen and the VVB audit

> [!NOTE]
>
> In all cases, guidance provided in the [Isometric Standard](https://registry.isometric.com/standard), [Protocols](https://registry.isometric.com/protocols) and [Modules](https://registry.isometric.com/modules) is authoritative.

## What are sub-requirements?

Sub-requirements sit nested under a main [project design requirement](https://docs.isometric.com/user-guides/certify/project-design.md). Projects must ensure that all sub-requirements are clearly addressed in their submission; if a requirement has six sub-requirements, your submission must explicitly address all six. During audit, VVBs will typically raise an issue against any sub-requirement that is missing or unanswered.

## Can I use attachments in place of written submissions?

Evidence attachments are encouraged, but should not replace a written explanation.

For each attachment, explain in the submission what it shows and why it is relevant. Where it helps, quote the text and give page numbers so a reviewer can find the section quickly. This will speed up both the Isometric pre-screen stage and the VVB audit stage, allowing you to complete these steps more efficiently.

## Still need help?

If none of these answers solve your problem, [contact support](https://docs.isometric.com/support/contact-support.md).


## Related topics

- [Certify and data FAQs](https://docs.isometric.com/support/platform/certify-and-data.md)
- [Isometric Support](https://docs.isometric.com/support/index.md)
- [Onboarding, process and timelines FAQs](https://docs.isometric.com/support/working-with-isometric/onboarding-and-timelines.md)


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