[expr.rel] Clarify auxiliary partial ordering (#1977)

Author: jensmaurer

source/expressions.tex

@@ -5073,27 +5073,27 @@
 After conversions, the operands shall have the same type.
 
 \pnum
-Comparing unequal pointers to objects%
+The result of comparing unequal pointers to objects%
 \footnote{An object that is not an array element is considered to belong to a
 single-element array for this purpose; see~\ref{expr.unary.op}.
 A pointer past the last element of an array \tcode{x} of $n$ elements
 is considered to be equivalent to a pointer to a hypothetical element
 $\mathtt{x[}n\mathtt{]}$ for this purpose; see~\ref{basic.compound}.}
-is defined as follows:
+is defined in terms of a partial order consistent with the following rules:
 
 \begin{itemize}
 \item If two pointers point to different elements of the same array, or to
 subobjects thereof, the pointer to the element with the higher subscript
-compares greater.
+is required to compare greater.
 
 \item If two pointers point to different non-static data members of the same
 object, or to subobjects of such members, recursively,
-the pointer to the later declared member compares greater provided
+the pointer to the later declared member is required to compare greater provided
 the two members have the same access control\iref{class.access},
 neither member is a subobject of zero size,
 and their class is not a union.
 
-\item Otherwise, neither pointer compares greater than the other.
+\item Otherwise, neither pointer is required to compare greater than the other.
 
 \end{itemize}