function CharacterKnowledge.AddTooltipExtension( tooltip, itemLink, server, charIdMotif )
	-- Abort if the item is not something we can handle
	local category = LCK.GetItemCategory(itemLink)
	if (category == LCK.ITEM_CATEGORY_NONE) then return end

	-- Initialize
	local pinnedChars = CharacterKnowledge.serverVars.tooltips.pinnedCharsForChapters
	local itemColors = CharacterKnowledge.vars.tooltips.itemColors
	local charColors = CharacterKnowledge.vars.tooltips.charColors
	LEJ.TooltipExtensionInitialize(true)

	local knownList = {}

	-- Motif knowledge sections
	if (category == LCK.ITEM_CATEGORY_MOTIF) then
		local items = LCK.GetMotifItemsFromStyle(LCK.GetStyleAndChapterFromMotif(itemLink))

		if (items and #items.chapters > 0) then
			local includedCharIds = { [CharacterKnowledge.charId] = true }
			if (charIdMotif) then
				includedCharIds[charIdMotif] = true
			end
			for i, character in ipairs(LCK.GetItemKnowledgeList(itemLink, server, includedCharIds)) do
					local chapters = { }
					local known = 0
					knownList[character.id] = 0
					for _, chapter in ipairs(LCK.GetMotifChapterNames()) do
						local knowledge = LCK.GetItemKnowledgeForCharacter(items.chapters[chapter.id], server, character.id)
						if (LCK.IsKnowledgeUsable(knowledge)) then
							if (i <= pinnedChars or includedCharIds[character.id]) then 
								table.insert(chapters, string.format("|c%06X%s|r", itemColors[knowledge], chapter.name))
							end
							if (knowledge == LCK.KNOWLEDGE_KNOWN) then
								known = known + 1
								knownList[character.id] = knownList[character.id] + 1
							end
						end
					end

					if (#chapters > 0) then
						LEJ.TooltipExtensionAddSection(
							string.format("%s (%d/%d)", character.name, known, #chapters),
							(known < #chapters) and table.concat(chapters, ", ") or string.format("|c%06X%s|r", itemColors[LCK.KNOWLEDGE_KNOWN], GetString(SI_ACHIEVEMENTS_TOOLTIP_COMPLETE))
						)
					end
			end
		end
	end

	-- Characters section
	local characters = LCK.GetItemKnowledgeList(itemLink, server)
	if (#characters > 0) then
		local results = { }
		local found = 0

		for _, character in ipairs(characters) do
			if (character.id == CharacterKnowledge.charId) then
				if knownList[character.id] then
					table.insert(results, string.format("|c%06X|l0:1:1:1:1:%06X|l%s(%s)|l|r", charColors[character.knowledge], charColors[character.knowledge], character.name, knownList[character.id]))
				else
					table.insert(results, string.format("|c%06X|l0:1:1:1:1:%06X|l%s|l|r", charColors[character.knowledge], charColors[character.knowledge], character.name))
				end
			else
				if knownList[character.id] then
					table.insert(results, string.format("|c%06X%s(%s)|r", charColors[character.knowledge], character.name, knownList[character.id]))
				else
					table.insert(results, string.format("|c%06X%s|r", charColors[character.knowledge], character.name))
				end
			end
			if (character.knowledge == LCK.KNOWLEDGE_KNOWN) then
				found = found + 1
			end
		end

		LEJ.TooltipExtensionAddSection(
			string.format("%s (%d/%d)", GetString(SI_CK_TT_HEADER), found, #characters),
			table.concat(results, ", ")
		)
	end

	LEJ.TooltipExtensionFinalize(tooltip)
end