Data structure and structural relationships
Your citation is incorrect--this is on page 232 in 3rd edition, not 252 (first paragraph of &quot;Information Structures&quot;, chapter 2.1.
Based on having the chapter available, Knuth is talking about data structures in general. I agree the with suggestions above--just ignore this paragraph if it doesn't make sense or seems obvious. I personally agree that it does not seem to define anything or communicate anything clear to me.