Modifying Filter Registration

File types are associated with file-name extensions under the \HKEY_LOCAL_MACHINE\SOFTWARE\Classes tree. Following are the associations for htmlfile document type:

\HKEY_LOCAL_MACHINE\SOFTWARE\Classes
   .htm
        = REG_SZ htmlfile
    .html
        = REG_SZ htmlfile
    .htx
        = REG_SZ htmlfile
    .stm
        = REG_SZ htmlfile

By default, the extensions listed above are considered to be htmlfile documents. To add another extension to this list, an entry must be created in the registry associating that extension with htmlfile type. For example, to treat .htx files as htmlfile type, add the following entry:

\HKEY_LOCAL_MACHINE\SOFTWARE\Classes
   .htx
        = REG_SZ htmlfile

Caution    Editing the registry incorrectly can cause serious problems, including corruption that may make it necessary to reinstall Windows NT or Microsoft Index Server. Using the Registry Editor (regsvr32.exe) to edit entries in the registry is equivalent to editing raw sectors on a hard disk. If you make mistakes, your computer’s configuration could be damaged. You should edit registry entries only for settings that you cannot adjust through the user interface, and be very careful whenever you edit the registry directly.

This topic contains:

• Removing a Filter
• Registering File Types as Binary Files

Removing a Filter

The example in this section shows how to remove the installed nlhtml.dll. You must remove the following two entries:

\Registry\Machine\Software\Classes\CLSID
     {EEC97550-47A9-11CF-B952-00AA0051FE20}
        PersistentAddinsRegistered
            {89BCB740-6119-101A-BCB7-00DD010655AF}
                = REG_SZ {E0CA5340-4534-11CF-B952-00AA0051FE20}

\Registry\Machine\Software\Classes\CLSID
     {E0CA5340-4534-11CF-B952-00AA0051FE20}
        = REG_SZ HTML Filter
        InprocServer32
            = REG_SZ nlhtml.dll

Registering File Types as Binary Files

A file with a certain extension is considered to be a binary file if its type in the registry is set to BinaryFile. For example, to associate the extension .lib with the binary file type, add the following entry to the registry:

\HKEY_LOCAL_MACHINES\Software\Classes
  \.lib
        = REG_SZ BinaryFile

The class BinaryFile is a pre-defined type that uses the NULL filter for its IFilter implementation.

Warning    If the extension for which you wish to use the NULL filter already has a file type, do not change it to BinaryFile. Doing so could damage your Windows NT installation. Instead, use the following procedure to set the implementation of the IFilter interface for the file type.

When a file-name extension already has a file type, use the previous procedure to look up the PersistentAddinsRegistered key and set the IFilter interface implementation. The example below is for files with the extension .dll.

Step 1: Determine the file type

Find the file type associated with the extension .dll.

\HKEY_LOCAL_MACHINE\Software\Classes
        \.dll
            = REG_SZ dllfile

Step 2: Determine the CLSID

Look up the CLSID associated with the dllfile type in the registry.

\HKEY_LOCAL_MACHINE\Software\Classes
        dllfile
            = REG_SZ Application Extension
            CLSID
                = REG_SZ {3cf51a00-84eb-11ce-ac07-00004c752752}

Step 3: Determine the Persistent Handler

Look up the persistent handler GUID for the CLSID in the registry. If there is no persistent handler, set it to the CLSID for the persistent handler of the NULL filter, “{098F2470-BAE0-11CD-B579-08002B30BFEB}”. Otherwise, continue with the next step.

\HKEY_LOCAL_MACHINE\Software\Classes
        CLSID
            {3cf51a00-84eb-11ce-ac07-00004c752752}
                PersistentHandler
                    = REG_SZ {098F2470-BAE0-11CD-B579-08002B30BFEB}

Step 4: Set the IFilter Persistent Handler

Look up the CLSID found in step 3 above and set the IFilter handler {89BCB740-6119-101A-BCB7-00DD010655AF} to the NULL filter GUID {C3278E90-BEA7-11CD-B579-08002B30BFEB}.

\HKEY_LOCAL_MACHINE\Software\Classes
        CLSID
            {098F2470-BAE0-11CD-B579-08002B30BFEB}
                 PersistentAddinsRegistered
                     {89BCB740-6119-101A-BCB7-00DD010655AF}
                          = REG_SZ {C3278E90-BEA7-11CD-B579-08002B30BFEB}

Here is a list of default extensions for binary files:

.aif, .asf, .avi, .bsc, .cab, .cgm, .com, .dct, .dic, .dll, .exe, .eyb,
.fnt, .ghi, .gif, .hqx, .ico, .inv, .jbf, .jpg, .m14, .mov, .movie,
.mv, .pdf, .pic, .pma, .pmc, .pml, .pmr, .psd, .sbr, .sc2, .sys,
.tar, .tif, .tiff, .ttf, .wav, .wll, .wlt, .wmf, .xix, .z, .z96, .zip

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