How does SharePoint apis/methods decide to apply 'AddAndCustomizePages' permission on lists/items.

Question

User need 'AddAndCustomizePages' permission to create/update some lists and its items. How does SharePoint apis decide to which some lists 'AddAndCustomizePages' permission will be applied. If we don't have that permission we get access denied error.

For example. we need 'AddAndCustomizePages' permission to update composed looks list or converted forms list and its items but for documents or site assets we don't need. why so?

If we say it is due to system list then site asset is also system list then why don't we need permission for it?

Can you please explain what is the login being used here?

Note: AddAndCustomizePages means 'DenyAddAndCustomizePages' can be set through PowerShell or custom script through SharePoint setting.

Thanks in advance!

@RaytheonXie_MSFT

Answer 1

Hi @Yuvraj Patil ,
As the description in the document, Add and Customize Pages is for Add, change, or delete HTML pages or Web Part pages, and edit the website.. And the composed looks list stores the files control including colors, fonts, and a background image, to your SharePoint. So when you update the items in the list, you will need 'AddAndCustomizePages' permission. Site Assets is used to store all the content and files necessary for a SharePoint site to function properly (i.e. Logos, OneNote notebook, etc.). It is not a library where you will store working files and content. The library is sort of a dumping ground for everything you used to build your site – things are added to it automatically as you do this. 'AddAndCustomizePages' permission isn't necessary for us to update it.

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