A Final Word About Identifiers
There is a bit of chicanery going on here with respect to unique identifiers. By the time a system is to be built, the analysts will have to address the problem of uniquely identifying Facilities (for example), along with all of the other elements described in this book.
The easiest way to do it of course would be to have a Global Site Identifier that applies to all physical sites. But many sites, like bridges and highways and oil wells, have identifiers already, issued according to a scheme that is very old. In other cases, however, identification has not really been addressed.
This is a book about model patterns. It is intended as a starting point. In each case, your author surmised an identification scheme that ...