1.	In .h files the following identifiers must be surrounded by
	the PEGASUS_STD() macro (which prepends std:: to the argument).

	    ostream
	    istream
	    cout
	    cerr

	Do not use this macro in .cpp files. Instead put the following
	at the beginning of the file:

	    PEGASUS_USING_STD;

    2.	The following does not compile with some compilers.

	    class X
	    {
	    public:

		static const Uint32 COLOR = 225;
	    };

	Use this instead:

	    class X
	    {
	    public:

		static const Uint32 COLOR;
	    };

	And place this in the .cpp file:

	    const Uint32 X::COLOR = 255;

	Or use enumerated types:

	    class X
	    {
	    public:

		enum { COLOR = 225 };
	    };

    3.	Explain use of Linkage.h files and linkage directives.