Question about leading underscores

From: rwgk_at_[hidden]
Date: 2001-06-22 17:18:16

In the header file boost/utility.hpp, leading underscores are
are used for some variable names:

    template <class A, class B>
    class tied {
    public:
      inline tied(A& a, B& b) : _a(a), _b(b) { }
      /...
    protected:
      A& _a;
      B& _b;
    };

I always thought that identifiers with leading underscores
should not be used. Is this only true for identifieres
in the global namespace?

Thanks!
        Ralf