Why does Stroustrup's book demonstrate default function template arguments, which weren't allowed at the time?

Question

Can anyone explain me why in chapter 13 of the third edition of C++ Programming Language, Stroustrup illustrates default parameters for function templates, although they are not supported by C++ (pre C++11)? This is the example given by Stroustrup in section 13.4.1:

Explicitly specifying the comparison for each call is tedious. Fortunately, it is easy to pick a default so that only uncommon comparison criteria have to be explicitly specified. This can be implemented through overloading:

template<class T, class C>
int compare(const String<T>& str1, const String<T>& str2); // compare using C
template<class T>
int compare(const String<T>& str1, const String<T>& str2); // compare using Cmp<T>

Alternatively, we can supply the normal convention as a default template argument:

template <class T, class C = Cmp<T> >
int compare(const String<T>& str1, const String<T>& str2)

and this is the compiler error:

error: default template arguments may not be used in function templates

Answer 1

The author himself explains this on his web site:

Due to an unfortunate oversight, the standard simply bans default arguments for template parameters for a function template. Voted to be corrected in the next standard.