IDS_MERGE_FATAL_INCOMPDTD
Fatal Error: Incompatible DTD Version: <version>
Given when you attempt to merge a set of compiled Help (.HxS) files that were created using a different version of the Microsoft Help DTDs. The DTD version of the .HxS files should match the version that is installed on the local computer.
The DTD version for an .HxS file can be found in the value of the DTDVersion attribute in the collection definition (.HxC) file used to compile the .HxS file.
To correct this error
If the version shown in the error message is newer than that installed on the local computer, install the latest version of Microsoft Help, recompile the .HxS files, and perform the merge again.
-or-
If the version shown in the error message is older than that installed on the local computer, recompile the .HxS files using the latest version of Microsoft Help, and perform the merge again.