/// <summary>
        /// Writes the value expressed as a <c>number</c>, which is the articulation value.
        /// </summary>
        /// <param name="dates">The dates at which the value is specified.</param>
        /// <param name="values">The value corresponding to each date.</param>
        /// <param name="startIndex">The index of the first element to write.</param>
        /// <param name="length">The number of elements to write.</param>
        public void WriteNumber(IList <JulianDate> dates, IList <double> values, int startIndex, int length)
        {
            const string PropertyName = NumberPropertyName;

            OpenIntervalIfNecessary();
            CesiumWritingHelper.WriteDouble(Output, PropertyName, dates, values, startIndex, length);
        }