1. Important Note
This list originated from an 'official' list of four-character codes. However, this list is not ideal for the purpose, so it has developed (and will continue to develop). To this end, note that codes displayed in green are not from the original 'official' list, but are in use; since they do not clash with any other codes so they are now effectively 'official'. On the other hand, codes displayed in red could result in a name clash with another unit. If using these codes at the beginning of a computer name, you must include a hyphen immediately after the code to prevent a clash with another unit identifier.