US International Extended Keyboard Layout. Basically the US Int layout you can get in Linux, but for Windows. The description of the keyboard with all available characters can be found here: http://dry.sailingissues.com/us-international-keyboard-layout.html
The main benefit is that it includes far more dead keys for accents than the standard US Intl Keyboard from Windows.
/usintext directory contains the executable setup and installation files. However, if you have the Microsoft Keyboard Layout Creator tool (download for free from ttps://msdn.microsoft.com/en-us/goglobal/bb964665.aspx) you can compile or customize your own with the project file included in the root. MSKLC needs .NET Framework 3.5, so for Windows 11 users the easiest way is to enable .NET Framework 3.5 in the Windows Features system menu.
After installing it, in Windows, go to Settings > Time & Language > Region & Language, and under Languages, add English (United States) if you had not already added it. After that go to Options, and under Keyboards you should see "United States-International - Extended", which is the layout corresponding to this project.