SPBasePermissions Demystified

Read It

SharePoint Foundation has defined built-in permissions Represented by class RoleDefinitions in Object model. In addition to the built-in permissions you have an option of creating a new Permission Level (RoleDefinition) also as per your needs.

Everything you access in SharePoint revolves around the permissions defined within the site. To view the level of permissions that your site has use http://YourSite/_layouts/role.aspx.

How Its Done

It is important to note that permission defined in SharePoint represents a single binary digit. When you want to assign multiple permission to a single role you will need to use bitwise operator OR for it.

For instance, users with ViewListItems, EditListItems, AddListItmes and DeleteListItems permissions will have decimal 15 or hex 0xF as their permissions mask.

0001 (0x1, 1) ViewListItems

0010 (0x2, 2) EditListItems

0100 (0x3, 4) AddListItmes

OR 1000 (0x4, 8 ) DeleteListItems

= 1111 (0xF, 15)

As you can see SPBasePermissions enum is representing in hex and stored as unsigned long.

For more information on SPBasePermissions Enumeration refer: http://msdn.microsoft.com/en-us/library/microsoft.sharepoint.spbasepermissions.aspx

Finally

Here is the complete table of permissions with their hex and decimal values:

I found an interesting post on SharePoint Permission Dependency Chart here: http://skurocks.wordpress.com/2008/09/20/sharepoint-permission-dependency-chart/