[locale.moneypunct.virtuals] Add reference to ISO 4217. (#1779)

Author: jensmaurer

source/back.tex

@@ -9,7 +9,10 @@ \chapter{Bibliography}
 \item
   ISO/IEC 10967-1:2012,
   \doccite{Information technology --- Language independent arithmetic ---
-           Part 1: Integer and floating point arithmetic}
+    Part 1: Integer and floating point arithmetic}
+\item
+  ISO 4217:2015,
+  \doccite{Codes for the representation of currencies}
 \end{itemize}
 
 The arithmetic specification described in ISO/IEC 10967-1:2012 is

source/locales.tex

@@ -4779,10 +4779,12 @@
 \begin{itemdescr}
 \pnum
 \returns
-A string to use as the currency identifier symbol.\footnote{For international
-specializations (second template parameter
-\tcode{true})
-this is typically four characters long, usually three letters and a space.}
+A string to use as the currency identifier symbol.
+\begin{note}
+For specializations where the second template parameter is \tcode{true},
+this is typically four characters long: a three-letter code as specified
+by ISO 4217 followed by a space.
+\end{note}
 \end{itemdescr}
 
 \indexlibrarymember{moneypunct}{do_positive_sign}%
@@ -4835,7 +4837,7 @@
 initialized to
 \tcode{\{ symbol, sign, none, value \}}.\footnote{Note that the international
 symbol returned by
-\tcode{do_curr_sym()}
+\tcode{do_curr_symbol()}
 usually contains a space, itself;
 for example, \tcode{"USD "}.}
 \end{itemdescr}