Syntax of .Reg Files

A .reg file has the following syntax:

RegistryEditorVersion
Blank line
[RegistryPath1]
"DataItemName1"="DataType1:DataValue1"
DataItemName2"="DataType2:DataValue2"
Blank line
[RegistryPath2]
"DataItemName3"="DataType3:DataValue3"

where:

RegistryEditorVersion is either "Windows Registry Editor Version 5.00" for Windows 2000, Windows XP, and Windows Server 2003, or "REGEDIT4" for Windows 98 and Windows NT 4.0. The "REGEDIT4" header also works on Windows 2000-based, Windows XP-based, and Windows Server 2003-based computers.

Blank line is a blank line. This identifies the start of a new registry path. Each key or subkey is a new registry path. If you have several keys in your .reg file, blank lines can help you to examine and to troubleshoot the contents.
RegistryPathx is the path of the subkey that holds the first value you are importing. Enclose the path in square brackets, and separate each level of the hierarchy by a backslash. For example:

[HKEY_LOCAL_ MACHINESOFTWAREPoliciesMicrosoftWindowsSystem]

A .reg file can contain several registry paths. If the bottom of the hierarchy in the path statement does not exist in the registry, a new subkey is created. The contents of the registry files are sent to the registry in the order you enter them. Therefore, if you want to create a new subkey with another subkey below it, you must enter the lines in the correct order.

DataItemNamex is the name of the data item that you want to import. If a data item in your file does not exist in the registry, the .reg file adds it (with the value of the data item). If a data item does exist, the value in your .reg file overwrites the existing value. Quotation marks enclose the name of the data item. An equal sign (=) immediately follows the name of the data item.

DataTypex is the data type for the registry value and immediately follows the equal sign. For all the data types other than REG_SZ (a string value), a colon immediately follows the data type. If the data type is REG_SZ , do not include the data type value or colon. In this case, Regedit.exe assumes REG_SZ for the data type.

The following table lists the typical registry data types:

For more information about registry data types, click the following article number to view the article in the Microsoft Knowledge Base:

256986 (http://support.microsoft.com/kb/256986/ ) Description of the Microsoft Windows registry

DataValuex immediately follows the colon (or the equal sign with REG_SZ) and must be in the appropriate format (for example, string or hexadecimal). Use hexadecimal format for binary data items.
Note You can enter several data item lines for the same registry path.
Note the registry file should contain a blank line at the bottom of the file.

Reference: How to add, modify, or delete registry subkeys and values by using a registration entries (.reg) file