Going throught a Mozilla Firefox package we looked at the Applicability rules between the update and the full install. The full install is looking for the presence of a registry key and file version while the update looks only for the existance of a mozilla registry key along with the version information like the full install package.
Wouldn't the full installer look for the absence of mozilla registry keys? Why is it that if the registry key exists and is equial to or lower than what is looked for or if the key doesn't exist at all does the install still continue? Is there a default value that gets passed when the key doesn't exist and do we have to watch out for this in our own packages?
