Does the bundle ID have to use reverse domain notation?

Question

Does an app bundle ID have to use reverse domain notation, or can it be anything as long as it's unique, for example companyname.myappname?

Answer 1

According to Apple Developer Documentation, under 'About Bundle IDs' section:

The bundle ID string must be a uniform type identifier (UTI) that contains only alphanumeric characters (A-Z,a-z,0-9), hyphen (-), and period (.). The string should be in reverse-DNS format. For example, if your organization’s domain is Acme.com and you create an app named Hello, you could assign the string com.Acme.Hello as your app’s bundle ID.

It says string SHOULD be in revers-DNS, not MUST be!