[lex.pptoken] Do not use terms before they are defined

source/lex.tex

@@ -509,11 +509,6 @@
     \textnormal{each non-whitespace character that cannot be one of the above}
 \end{bnf}
 
-\pnum
-Each preprocessing token that is converted to a token\iref{lex.token}
-shall have the lexical form of a keyword, an identifier, a literal,
-or an operator or punctuator.
-
 \pnum
 A preprocessing token is the minimal lexical element of the language in translation
 phases 3 through 6.
@@ -548,6 +543,22 @@
 between the quotation characters in a character literal or
 string literal.
 
+\pnum
+Each preprocessing token that is converted to a token\iref{lex.token}
+shall have the lexical form of a keyword, an identifier, a literal,
+or an operator or punctuator.
+
+\pnum
+The \grammarterm{import-keyword} is produced
+by processing an \keyword{import} directive\iref{cpp.import},
+the \grammarterm{module-keyword} is produced
+by preprocessing a \keyword{module} directive\iref{cpp.module}, and
+the \grammarterm{export-keyword} is produced
+by preprocessing either of the previous two directives.
+\begin{note}
+None has any observable spelling.
+\end{note}
+
 \pnum
 If the input stream has been parsed into preprocessing tokens up to a
 given character:
@@ -587,24 +598,14 @@
 \end{itemize}
 \end{itemize}
 
+\pnum
 \begin{example}
 \begin{codeblock}
 #define R "x"
 const char* s = R"y";           // ill-formed raw string, not \tcode{"x" "y"}
 \end{codeblock}
 \end{example}
 
-\pnum
-The \grammarterm{import-keyword} is produced
-by preprocessing an \keyword{import} directive\iref{cpp.import},
-the \grammarterm{module-keyword} is produced
-by preprocessing a \keyword{module} directive\iref{cpp.module}, and
-the \grammarterm{export-keyword} is produced
-by preprocessing either of the previous two directives.
-\begin{note}
-None has any observable spelling.
-\end{note}
-
 \pnum
 \begin{example}
 The program fragment \tcode{0xe+foo} is parsed as a