Registry data types.

REG_BINARY: binary data is stored as a string of hex pairs where each pair give a range of 0 to 255. REG_BINARY can be any length. In WinNT, REG_BINARY entries are rare. Most of the entries that are used in binary format are limited to 32 bits and then are used as REG_DWORD entries. If a REG_DWORD entry were mistakenly entered as a REG_BINARY entry, it would still work without a problem. REG_BINARY entries simply have the flexibility to be longer as well as possibly contain raw data such as encrypted passwords.

REG_DWORD: indicates that the data data stored in a double word, a four-byte number (32-bits). Words can range in value from 0 - 4GB. Always displayed as 4 bytes. Device drivers and services parameters are often of this type and can be viewed in binary, hex, or decimal using the Registry editor.

REG_EXPAND_SZ: indicates an expandable string which really is a variable. For example, %SystemRoot%\SYSTEM32\config is an expandable string that is replaced when the real value when the string is called by an application.

REG_FULL_RESOURCE_DESCRIPTOR: Used in hardware registry keys. Do not edit this type of key.

REG_LINK: The value points to another key or value. Three of the six Registry root keys, HKEY_CURRENT_USER, HKEY_CLASSES_ROOT and HKEY_CURRENT_CONFIG are links to subkeys within the three non-link root keys, HKEY_USERS, HKEY_LOCAL_MACHINE, and HKEY_DYN_DATA.