What does square brackets [ ] syntax mean in WiX

Question

I\'m creating an installer for IIS website using WiX toolset and using this manual. I\'ve came across following syntax

Answer 1

This is the way that Windows Installer properties are resolved to the actual values. If you entered a property called WEBSITE into an MSI dialog you'd get that resolved to the actual value by putting it in square brackets. That's why you see things like [TARGETDIR], [SourceDir] and so on. The syntax is used in most tools that generate MSI files because it's a Windows Installer thing.

This is the doc link, it's all hidden here:

Formatted Windows Installer

So 1 - they are properties in the MSI file, either standard Windows Installer properties or user-created ones:

Property Reference

and 2, they are just two properties concatenated. They are case-sensitive so don't be sloppy with the case. The other points should be clear after understanding that they are installer properties.

The $() values in WiX source are compile time - they resolve at build time to actual values. The [] values resolve at install time.