What is the function of the "this" keyword in a constructor?

I was looking at sample code from MSDN just now and came accross:

namespace IListSourceCS
{
    public class Employee : BusinessObjectBase
    {
        private string      _id;
        private string      _name;
        private Decimal     parkingId;

        public Employee() : this(string.Empty, 0) {} // <<--- WHAT IS THIS???
        public Employee(string name) : this(name, 0) {}