Each data entry in the metabase is assigned a unique identifier. An identifier is a DWORD containing a number that uniquely identifies the data in the metabase. Identifiers used by IIS are assigned from a pool of reserved numbers. The first 32K is reserved by the system for IIS data and the second 32K is reserved for Microsoft® FrontPageÖ data. If you create identifiers in the metabase, use identifier numbers greater than 65535 (0x0000ffff) to avoid conflicts with current or future system data.
Each identifier is also assigned a user type, which is a DWORD that specifies how the data is used. Current IIS user types include IIS_MD_UT_SERVER for server configuration parameters, IIS_MD_UT_FILE for file and directory properties, IIS_MD_UT_WAM for web application management, and ASP_MD_UT_APP for ASP application configuration. User types enable you to classify your identifiers by application. You must assign a user type to each identifier you create in the metabase, although each identifier is not required to have a unique user type. The numbers from 0 to 2,000 are reserved for current and future system user types. User types you create must be above 2,000 to avoid conflicts with current and future system user types.
You can use the user type to filter data requested from a key. For example, the GetAllData method has a parameter, dwUserType, you can use to specify that only data of a certain user type is to be returned. For example, if this parameter is set to IIS_MD_UT_SERVER during the method call, only data related to the server will be returned.
Note Metabase identifiers must be unique, but multiple identifiers can have the same user type and data type.