sealed class NumberingListStyleCollection
	{
		//...
        private int maxlevelDepth = 0;
		//...
		public void BeginList(HtmlEnumerator en)
		{
			int prevAbsNumId = absNumId;

			// lookup for a predefined list style in the template collection
			String type = en.StyleAttributes["list-style-type"];
			bool orderedList = en.CurrentTag.Equals("<ol>", StringComparison.OrdinalIgnoreCase);
			if (type == null || !knonwAbsNumIds.TryGetValue(type.ToLowerInvariant(), out absNumId))
			{
				if (orderedList)
					absNumId = knonwAbsNumIds["decimal"];
				else
					absNumId = knonwAbsNumIds["disc"];
			}

			firstItem = true;
			levelDepth++;

			// save a NumberingInstance if the nested list style is the same as its ancestor.
			// this allows us to nest <ol> and restart the indentation to 1.
			int currentInstanceId = this.InstanceID;
			if (levelDepth > 1 && absNumId == prevAbsNumId && orderedList)
			{
				EnsureMultilevel(absNumId);
			}
			else
			{
                // For unordered lists (<ul>), create only one NumberingInstance per level
                // (MS Word does not tolerate hundreds of identical NumberingInstances)
                if (orderedList || (levelDepth > maxlevelDepth))
                {
                    if (levelDepth > maxlevelDepth)
                    {
                        maxlevelDepth = levelDepth;
                    }

                    currentInstanceId = ++nextInstanceID;

				    Numbering numbering = mainPart.NumberingDefinitionsPart.Numbering;

                    numbering.Append(
                        new NumberingInstance(
                            new AbstractNumId() { Val = absNumId },
                            new LevelOverride(
                                new StartOverrideNumberingValue() { Val = 1 }
                            ) { LevelIndex = 0, }
                        ) { NumberID = currentInstanceId });
                }
			}

			numInstances.Push(currentInstanceId);
		}