Search notes:

%appdata%\Microsoft\Excel\XLSTART

%appdata%\Microsoft\Excel\XLSTART is a directory where Excel searches for workbook templates and the Personal.xlsb.
Whenever Excel is started, it opens all Workbooks that it finds in the XLSTART file.
This directory is in the default list of MS Office: Trust Center - Trusted Locations for Excel, Word and PowerPoint.

Templates

The special (template) files (.xltx, .xltm) Book.xlt* and Sheet.xlt* are used as defaults when a new Excel workbook or worksheet is created.
Apparently, in non English installations of Excel, the names of these files are subject to localization. For example, in a french installation, their respective names are Livre.xltx and Feuille.xltx.
TODO: when a workbook is created with File -> New -> Blank Workbook, the template file seems not to be considered.

Finding the XLSTART directory

The default location for XLSTART is %appdata%\Microsoft\Excel\XLSTART.
If this directory is not found under the default location, it might be found by executing (querying really) application.startupPath in the immediate window.

See also

A similar role, but for all users, seems to have the directory C:\Program Files\Microsoft Office\root\OfficeX\XLSTART.
The AltStartup value under the registry key HKEY_CURRENT_USER\Software\Microsoft\Office\_version_\Excel\Options.

Index

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