I did my PhD in database in the early 80s. This book by W. Kent was around already and I heard about it but did not have a copy of it. Had I read the book, my research work would have been 10 times better. This current printing is the reprint of the original one. The author mentioned in the preface that he was asked to update the book but he didn't because he thought it was still up to date (and I absolutely agree).
If you are in data modeling and database area, believe me, this is a must read. It is about the philosophy of data modeling and how data and reality are related. In my opinion, its content cannot be obsolete. It is technology independent. The concept of naming and identification alone is priceless for data modelers. I can't believe I have been working in the database area for more than 30 years without it.