Files with .itmsp extension are ITunes Store Packages. They are data files used by iTunes Producer and Application Loader software. iTunes Producer publishes multimedia and books. Application Loader publishes applications. These files are usually from book design documents called .iba or .book.
To open .itmsp files, install software like iTunes or iBooks Author on Mac or Windows. Other programs also support this file type. The file likely should not be accessed directly by users. It probably cannot convert to other formats.
If you cannot open an .itmsp file, the file could be corrupted. The links in the registry could be wrong. Or the registry entry describing .itmsp could be deleted. Make sure a program supporting .itmsp is fully installed. If it still won’t open, the file itself could be damaged or linked incorrectly in the registry.
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