The registry is where Windows Mobile stores application and operating system configuration settings. The registry stores the settings in the registry in hives by using keys, values and data. Registry keys operate like folder in the file system to organize values and data. The value is a way to refer to a specific setting under a specific key. The data is used to store the setting which is paired with the value.

Generally the registry is not documented by Microsoft, OEMs or developers. So the documentation of registry settings is usually done via trial and error and may not be 100% accurate.

Note: Microsoft, OEMs and carriers do not support end users editing the registry. If you edit the regisry you do so at your own risk!


Registry Hive Organization

The registry hives are split into the following sections:

HKEY_Classes_Root (HKCR) - When an application is installed, it sets up a unique GUID for the application and associates selected file extensions or mime types with the application.

HKEY_Curret_User (HKCU) - This is where the application and operating system stores settings that are user specific.

HKEY_Local_Machine (HKLM) - This is where the operating system stores hardware settings.

HKEY_Users (HKU) - This is usually used to store data for each user profile. In Windows Mobile, this key visibile however it is not used.


Values

The values that can be stored in the registry are the following

REG_NONE - No type
REG_SZ - A string value (not encapsulated in quotes)
REG_EXPAND_SZ - An "expandable" string value that can contain environment variables
REG_BINARY - Binary data (any arbitrary data) usually represented in hex
REG_DWORD - A double word value, a 32-bit unsigned integer (numbers between 0 and 4,294,967,295
REG_MULTI_SZ - A multi-string value (an array of unique strings)

Note: Some registry keys may not be modified by the user of the Windows Mobile Device. Some keys are only able to be modified by Microsoft or the OEM.

Also see the following Wiki pages:

Registry Editors
Specific Registry Settings