diff --git a/Categories/Auras.lua b/Categories/Auras.lua
index b9a11d0..26aa665 100644
--- a/Categories/Auras.lua
+++ b/Categories/Auras.lua
@@ -215,7 +215,7 @@ DogTag:AddTag("Unit", "HasAura", {
 	end,
 	arg = {
 		'aura', 'string', '@req',
-		'unit', 'string', 'player',
+		'unit', 'string;undef', 'player'
 	},
 	ret = "boolean",
 	events = "Aura#$unit#$aura",
@@ -275,7 +275,7 @@ end
 DogTag:AddTag("Unit", "DruidForm", {
 	code = DruidForm,
 	arg = {
-		'unit', 'string', 'player',
+		'unit', 'string;undef', 'player'
 	},
 	ret = "string;nil",
 	events = "UNIT_DISPLAYPOWER#$unit;Aura#$unit#" .. MOONKIN_FORM .. ";Aura#$unit#" .. AQUATIC_FORM .. ";Aura#$unit#" .. FLIGHT_FORM .. ";Aura#$unit#" .. SWIFT_FLIGHT_FORM .. ";Aura#$unit#" .. TRAVEL_FORM .. ";Aura#$unit#" .. TREE_OF_LIFE,
@@ -313,7 +313,7 @@ DogTag:AddTag("Unit", "NumDebuffs", {
 		return currentNumDebuffs[unit]
 	end,
 	arg = {
-		'unit', 'string', 'player',
+		'unit', 'string;undef', 'player'
 	},
 	ret = "number",
 	events = "Aura#$unit",
@@ -333,7 +333,7 @@ DogTag:AddTag("Unit", "AuraDuration", {
 	end,
 	arg = {
 		'aura', 'string', '@req',
-		'unit', 'string', 'player',
+		'unit', 'string;undef', 'player'
 	},
 	events = "Update",
 	ret = "number;nil",
@@ -346,7 +346,7 @@ local SHADOWFORM = GetSpellInfo(15473)
 DogTag:AddTag("Unit", "IsShadowform", {
 	alias = ("HasAura(aura=%q, unit=unit)"):format(SHADOWFORM),
 	arg = {
-		'unit', 'string', 'player',
+		'unit', 'string;undef', 'player'
 	},
 	doc = L["Return True if the unit has the shadowform buff"],
 	example = ('[IsShadowform] => %q; [IsShadowform] => ""'):format(L["True"]),
@@ -359,7 +359,7 @@ local PROWL = GetSpellInfo(5215)
 DogTag:AddTag("Unit", "IsStealthed", {
 	alias = ("HasAura(aura=%q, unit=unit) or HasAura(aura=%q, unit=unit) or HasAura(aura=%q, unit=unit)"):format(STEALTH, SHADOWFORM, PROWL),
 	arg = {
-		'unit', 'string', 'player',
+		'unit', 'string;undef', 'player'
 	},
 	doc = L["Return True if the unit is stealthed in some way"],
 	example = ('[IsStealthed] => %q; [IsStealthed] => ""'):format(L["True"]),
@@ -370,7 +370,7 @@ local SHIELD_WALL = GetSpellInfo(871)
 DogTag:AddTag("Unit", "HasShieldWall", {
 	alias = ("HasAura(aura=%q, unit=unit)"):format(SHIELD_WALL),
 	arg = {
-		'unit', 'string', 'player',
+		'unit', 'string;undef', 'player'
 	},
 	doc = L["Return True if the unit has the Shield Wall buff"],
 	example = ('[HasShieldWall] => %q; [HasShieldWall] => ""'):format(L["True"]),
@@ -381,7 +381,7 @@ local LAST_STAND = GetSpellInfo(12975)
 DogTag:AddTag("Unit", "HasLastStand", {
 	alias = ("HasAura(aura=%q, unit=unit)"):format(LAST_STAND),
 	arg = {
-		'unit', 'string', 'player',
+		'unit', 'string;undef', 'player'
 	},
 	doc = L["Return True if the unit has the Last Stand buff"],
 	example = ('[HasLastStand] => %q; [HasLastStand] => ""'):format(L["True"]),
@@ -392,7 +392,7 @@ local SOULSTONE_RESURRECTION = GetSpellInfo(20707)
 DogTag:AddTag("Unit", "HasSoulstone", {
 	alias = ("HasAura(aura=%q, unit=unit)"):format(SOULSTONE_RESURRECTION),
 	arg = {
-		'unit', 'string', 'player',
+		'unit', 'string;undef', 'player'
 	},
 	doc = L["Return True if the unit has the Soulstone buff"],
 	example = ('[HasSoulstone] => %q; [HasSoulstone] => ""'):format(L["True"]),
@@ -403,7 +403,7 @@ local MISDIRECTION = GetSpellInfo(34477)
 DogTag:AddTag("Unit", "HasMisdirection", {
 	alias = ("HasAura(aura=%q, unit=unit)"):format(MISDIRECTION),
 	arg = {
-		'unit', 'string', 'player',
+		'unit', 'string;undef', 'player'
 	},
 	doc = L["Return True if the unit has the Misdirection buff"],
 	example = ('[HasMisdirection] => %q; [HasMisdirection] => ""'):format(L["True"]),
@@ -414,7 +414,7 @@ local ICE_BLOCK = GetSpellInfo(27619)
 DogTag:AddTag("Unit", "HasIceBlock", {
 	alias = ("HasAura(aura=%q, unit=unit)"):format(ICE_BLOCK),
 	arg = {
-		'unit', 'string', 'player',
+		'unit', 'string;undef', 'player'
 	},
 	doc = L["Return True if the unit has the Ice Block buff"],
 	example = ('[HasIceBlock] => %q; [HasIceBlock] => ""'):format(L["True"]),
@@ -425,7 +425,7 @@ local INVISIBILITY = GetSpellInfo(66)
 DogTag:AddTag("Unit", "HasInvisibility", {
 	alias = ("HasAura(aura=%q, unit=unit)"):format(INVISIBILITY),
 	arg = {
-		'unit', 'string', 'player',
+		'unit', 'string;undef', 'player'
 	},
 	doc = L["Return True if the unit has the Invisibility buff"],
 	example = ('[HasInvisibility] => %q; [HasInvisibility] => ""'):format(L["True"]),
@@ -436,7 +436,7 @@ local DIVINE_INTERVENTION = GetSpellInfo(19752)
 DogTag:AddTag("Unit", "HasDivineIntervention", {
 	alias = ("HasAura(aura=%q, unit=unit)"):format(DIVINE_INTERVENTION),
 	arg = {
-		'unit', 'string', 'player',
+		'unit', 'string;undef', 'player'
 	},
 	doc = L["Return True if the unit has the Divine Intervention buff"],
 	example = ('[HasDivineIntervention] => %q; [HasDivineIntervention] => ""'):format(L["True"]),
@@ -449,7 +449,7 @@ DogTag:AddTag("Unit", "HasDebuffType", {
 	end,
 	arg = {
 		'type', 'string', '@req',
-		'unit', 'string', 'player',
+		'unit', 'string;undef', 'player'
 	},
 	ret = "boolean",
 	events = "Aura#$unit#$type",
@@ -461,7 +461,7 @@ DogTag:AddTag("Unit", "HasDebuffType", {
 DogTag:AddTag("Unit", "HasMagicDebuff", {
 	alias = ("HasDebuffType(type=%q, unit=unit)"):format(L["Magic"]),
 	arg = {
-		'unit', 'string', 'player',
+		'unit', 'string;undef', 'player'
 	},
 	doc = L["Return True if the unit has a Magic debuff"],
 	example = ('[HasMagicDebuff] => %q; [HasMagicDebuff] => ""'):format(L["True"]),
@@ -471,7 +471,7 @@ DogTag:AddTag("Unit", "HasMagicDebuff", {
 DogTag:AddTag("Unit", "HasCurseDebuff", {
 	alias = ("HasDebuffType(type=%q, unit=unit)"):format(L["Curse"]),
 	arg = {
-		'unit', 'string', 'player',
+		'unit', 'string;undef', 'player'
 	},
 	doc = L["Return True if the unit has a Curse debuff"],
 	example = ('[HasCurseDebuff] => %q; [HasCurseDebuff] => ""'):format(L["True"]),
@@ -481,7 +481,7 @@ DogTag:AddTag("Unit", "HasCurseDebuff", {
 DogTag:AddTag("Unit", "HasPoisonDebuff", {
 	alias = ("HasDebuffType(type=%q, unit=unit)"):format(L["Poison"]),
 	arg = {
-		'unit', 'string', 'player',
+		'unit', 'string;undef', 'player'
 	},
 	doc = L["Return True if the unit has a Poison debuff"],
 	example = ('[HasPoisonDebuff] => %q; [HasPoisonDebuff] => ""'):format(L["True"]),
@@ -491,7 +491,7 @@ DogTag:AddTag("Unit", "HasPoisonDebuff", {
 DogTag:AddTag("Unit", "HasDiseaseDebuff", {
 	alias = ("HasDebuffType(type=%q, unit=unit)"):format(L["Disease"]),
 	arg = {
-		'unit', 'string', 'player',
+		'unit', 'string;undef', 'player'
 	},
 	doc = L["Return True if the unit has a Disease debuff"],
 	example = ('[HasDiseaseDebuff] => %q; [HasDiseaseDebuff] => ""'):format(L["True"]),
diff --git a/Categories/Cast.lua b/Categories/Cast.lua
index 9236170..8ffa578 100644
--- a/Categories/Cast.lua
+++ b/Categories/Cast.lua
@@ -233,7 +233,7 @@ DogTag:AddTag("Unit", "CastName", {
 		return castData[unit].spell
 	end,
 	arg = {
-		'unit', 'string', 'player',
+		'unit', 'string;undef', 'player'
 	},
 	ret = "string;nil",
 	events = "Cast",
@@ -247,7 +247,7 @@ DogTag:AddTag("Unit", "CastTarget", {
 		return castData[unit].target
 	end,
 	arg = {
-		'unit', 'string', 'player',
+		'unit', 'string;undef', 'player'
 	},
 	ret = "string;nil",
 	events = "Cast",
@@ -261,7 +261,7 @@ DogTag:AddTag("Unit", "CastRank", {
 		return castData[unit].rank
 	end,
 	arg = {
-		'unit', 'string', 'player',
+		'unit', 'string;undef', 'player'
 	},
 	ret = "number;nil",
 	events = "Cast",
@@ -280,7 +280,7 @@ DogTag:AddTag("Unit", "CastStartDuration", {
 		end
 	end,
 	arg = {
-		'unit', 'string', 'player',
+		'unit', 'string;undef', 'player'
 	},
 	ret = "number;nil",
 	events = "FastUpdate;Cast#$unit",
@@ -299,7 +299,7 @@ DogTag:AddTag("Unit", "CastEndDuration", {
 		end
 	end,
 	arg = {
-		'unit', 'string', 'player',
+		'unit', 'string;undef', 'player'
 	},
 	ret = "number;nil",
 	events = "FastUpdate;Cast#$unit",
@@ -314,7 +314,7 @@ DogTag:AddTag("Unit", "CastDelay", {
 		return castData[unit].delay
 	end,
 	arg = {
-		'unit', 'string', 'player',
+		'unit', 'string;undef', 'player'
 	},
 	ret = "number;nil",
 	events = "Cast#$unit",
@@ -328,7 +328,7 @@ DogTag:AddTag("Unit", "CastIsChanneling", {
 		return not castData[unit].casting
 	end,
 	arg = {
-		'unit', 'string', 'player',
+		'unit', 'string;undef', 'player'
 	},
 	ret = "boolean",
 	events = "Cast#$unit",
@@ -347,7 +347,7 @@ DogTag:AddTag("Unit", "CastStopDuration", {
 		end
 	end,
 	arg = {
-		'unit', 'string', 'player',
+		'unit', 'string;undef', 'player'
 	},
 	ret = "number;nil",
 	events = "FastUpdate;Cast#$unit",
@@ -361,7 +361,7 @@ DogTag:AddTag("Unit", "CastStopMessage", {
 		return castData[unit].stopMessage
 	end,
 	arg = {
-		'unit', 'string', 'player',
+		'unit', 'string;undef', 'player'
 	},
 	ret = "string;nil",
 	events = "Cast#$unit",
diff --git a/Categories/Characteristics.lua b/Categories/Characteristics.lua
index 6bd31be..f093a74 100644
--- a/Categories/Characteristics.lua
+++ b/Categories/Characteristics.lua
@@ -417,7 +417,7 @@ DogTag:AddTag("Unit", "PvPRank", {
 	end,
 	arg = {
 		'value', 'string;undef', '@undef',
-		'unit', 'string', 'player',
+		'unit', 'string;undef', 'player'
 	},
 	ret = "string;nil",
 	events = "UNIT_NAME_UPDATE#$unit;PLAYER_ENTERING_WORLD#$unit",
@@ -475,7 +475,7 @@ DogTag:AddTag("Unit", "HostileColor", {
 	end,
 	arg = {
 		'value', 'string;undef', '@undef',
-		'unit', 'string', 'player',
+		'unit', 'string;undef', 'player'
 	},
 	ret = "string",
 	events = "UNIT_FACTION#$unit",
@@ -497,7 +497,7 @@ DogTag:AddTag("Unit", "AggroColor", {
 	end,
 	arg = {
 		'value', 'string;undef', '@undef',
-		'unit', 'string', 'player',
+		'unit', 'string;undef', 'player'
 	},
 	ret = "string",
 	events = "UNIT_FACTION#$unit",
@@ -518,7 +518,7 @@ DogTag:AddTag("Unit", "ClassColor", {
 	end,
 	arg = {
 		'value', 'string;undef', '@undef',
-		'unit', 'string', 'player',
+		'unit', 'string;undef', 'player'
 	},
 	ret = "string",
 	doc = L["Return the color or wrap value with the class color of unit"],
@@ -541,7 +541,7 @@ DogTag:AddTag("Unit", "DifficultyColor", {
 	end,
 	arg = {
 		'value', 'string;undef', '@undef',
-		'unit', 'string', 'player',
+		'unit', 'string;undef', 'player'
 	},
 	ret = "string",
 	events = "UNIT_LEVEL#$unit;PLAYER_LEVEL_UP#$unit",
@@ -553,7 +553,7 @@ DogTag:AddTag("Unit", "DifficultyColor", {
 DogTag:AddTag("Unit", "Guid", {
 	code = UnitGUID,
 	arg = {
-		'unit', 'string', 'player',
+		'unit', 'string;undef', 'player'
 	},
 	ret = "string",
 	doc = L["Return the GUID for the unit, an internal identifier."],
diff --git a/Categories/DruidMana.lua b/Categories/DruidMana.lua
index 2a41380..ce13ef4 100644
--- a/Categories/DruidMana.lua
+++ b/Categories/DruidMana.lua
@@ -42,7 +42,7 @@ DogTag:AddTag("Unit", "DruidMP", {
 	end,
 	dynamicCode = true,
 	args = {
-		'unit', 'string', 'player',
+		'unit', 'string;undef', 'player'
 	},
 	ret = "number;nil",
 	events = "DruidMana",
@@ -57,7 +57,7 @@ DogTag:AddTag("Unit", "MaxDruidMP", {
 	end,
 	dynamicCode = true,
 	args = {
-		'unit', 'string', 'player',
+		'unit', 'string;undef', 'player'
 	},
 	ret = "number;nil",
 	events = "DruidMana",
@@ -69,7 +69,7 @@ DogTag:AddTag("Unit", "MaxDruidMP", {
 DogTag:AddTag("Unit", "PercentDruidMP", {
 	alias = "[DruidMP(unit=unit) / MaxDruidMP(unit=unit) * 100]:Round(1)",
 	args = {
-		'unit', 'string', 'player',
+		'unit', 'string;undef', 'player'
 	},
 	doc = L["Return the percentage mana of unit if unit is you and you are a druid"],
 	example = '[PercentDruidMP] => "63.2"; [PercentDruidMP:Percent] => "63.2%"',
@@ -79,7 +79,7 @@ DogTag:AddTag("Unit", "PercentDruidMP", {
 DogTag:AddTag("Unit", "MissingDruidMP", {
 	alias = "MaxDruidMP(unit=unit) - DruidMP(unit=unit)",
 	args = {
-		'unit', 'string', 'player',
+		'unit', 'string;undef', 'player'
 	},
 	doc = L["Return the missing mana of unit if unit is you and you are a druid"],
 	example = ('[MissingDruidMP] => "%d"'):format(UnitManaMax("player")*.368),
@@ -89,7 +89,7 @@ DogTag:AddTag("Unit", "MissingDruidMP", {
 DogTag:AddTag("Unit", "FractionalDruidMP", {
 	alias = "Concatenate(DruidMP(unit=unit), '/', MaxDruidMP(unit=unit))",
 	args = {
-		'unit', 'string', 'player',
+		'unit', 'string;undef', 'player'
 	},
 	doc = L["Return the current and maximum mana of unit if unit is you and you are a druid"],
 	example = ('[FractionalDruidMP] => "%d/%d"'):format(UnitManaMax("player")*.632, UnitManaMax("player")),
@@ -99,7 +99,7 @@ DogTag:AddTag("Unit", "FractionalDruidMP", {
 DogTag:AddTag("Unit", "IsMaxDruidMP", {
 	alias = "Boolean(DruidMP(unit=unit) = MaxDruidMP(unit=unit))",
 	args = {
-		'unit', 'string', 'player',
+		'unit', 'string;undef', 'player'
 	},
 	doc = L["Return True if at max mana, unit is you, and you are a druid"],
 	example = ('[IsMaxDruidMP] => %q; [IsMaxDruidMP] => ""'):format(L["True"]),
diff --git a/Categories/Experience.lua b/Categories/Experience.lua
index 286897e..66a8afd 100644
--- a/Categories/Experience.lua
+++ b/Categories/Experience.lua
@@ -29,7 +29,7 @@ DogTag:AddTag("Unit", "XP", {
 		end
 	end,
 	arg = {
-		'unit', 'string', 'player',
+		'unit', 'string;undef', 'player'
 	},
 	ret = "number",
 	events = "UpdateExperience#$unit",
@@ -50,7 +50,7 @@ DogTag:AddTag("Unit", "MaxXP", {
 		end
 	end,
 	arg = {
-		'unit', 'string', 'player',
+		'unit', 'string;undef', 'player'
 	},
 	ret = "number",
 	events = "UpdateExperience#$unit",
@@ -62,7 +62,7 @@ DogTag:AddTag("Unit", "MaxXP", {
 DogTag:AddTag("Unit", "FractionalXP", {
 	alias = [[XP(unit=unit) "/" MaxXP(unit=unit)]],
 	arg = {
-		'unit', 'string', 'player',
+		'unit', 'string;undef', 'player'
 	},
 	doc = L["Return the current and maximum experience of unit"],
 	example = '[FractionalXP] => "8540/10000"',
@@ -72,7 +72,7 @@ DogTag:AddTag("Unit", "FractionalXP", {
 DogTag:AddTag("Unit", "PercentXP", {
 	alias = [[(XP(unit=unit) / MaxXP(unit=unit) * 100):Round(1)]],
 	arg = {
-		'unit', 'string', 'player',
+		'unit', 'string;undef', 'player'
 	},
 	doc = L["Return the percentage experience of unit"],
 	example = '[PercentXP] => "85.4"; [PercentXP:Percent] => "85.4%"',
@@ -82,7 +82,7 @@ DogTag:AddTag("Unit", "PercentXP", {
 DogTag:AddTag("Unit", "MissingXP", {
 	alias = [[MaxXP(unit=unit) - XP(unit=unit)]],
 	arg = {
-		'unit', 'string', 'player',
+		'unit', 'string;undef', 'player'
 	},
 	doc = L["Return the missing experience of unit"],
 	example = '[MissingXP] => "1460"',
@@ -98,7 +98,7 @@ DogTag:AddTag("Unit", "RestXP", {
 		end
 	end,
 	arg = {
-		'unit', 'string', 'player',
+		'unit', 'string;undef', 'player'
 	},
 	ret = "number",
 	events = "UpdateExperience#$unit",
@@ -110,7 +110,7 @@ DogTag:AddTag("Unit", "RestXP", {
 DogTag:AddTag("Unit", "PercentRestXP", {
 	alias = [[(RestXP(unit=unit) / MaxXP(unit=unit) * 100):Round(1)]],
 	arg = {
-		'unit', 'string', 'player',
+		'unit', 'string;undef', 'player'
 	},
 	doc = L["Return the percentage accumulated rest experience of unit"],
 	example = '[PercentRestXP] => "50"; [PercentRestXP:Percent] => "50%"',
diff --git a/Categories/GuildNote.lua b/Categories/GuildNote.lua
index c6b4f0a..af8753e 100644
--- a/Categories/GuildNote.lua
+++ b/Categories/GuildNote.lua
@@ -79,7 +79,7 @@ DogTag:AddTag("Unit", "GuildNote", {
 		return nil
 	end,
 	arg = {
-		'unit', 'string', 'player',
+		'unit', 'string;undef', 'player'
 	},
 	ret = "string;nil",
 	events = "GUILD_ROSTER_UPDATE",
@@ -97,7 +97,7 @@ DogTag:AddTag("Unit", "OfficerNote", {
 		return nil
 	end,
 	arg = {
-		'unit', 'string', 'player',
+		'unit', 'string;undef', 'player'
 	},
 	ret = "string;nil",
 	events = "GUILD_ROSTER_UPDATE",
diff --git a/Categories/Health.lua b/Categories/Health.lua
index 9b021b5..451e228 100644
--- a/Categories/Health.lua
+++ b/Categories/Health.lua
@@ -122,7 +122,7 @@ DogTag:AddTag("Unit", "HP", {
 	end,
 	dynamicCode = true,
 	arg = {
-		'unit', 'string', 'player',
+		'unit', 'string;undef', 'player',
 		'known', 'boolean', false,
 	},
 	ret = function(args)
@@ -144,7 +144,7 @@ DogTag:AddTag("Unit", "MaxHP", {
 	end,
 	dynamicCode = true,
 	arg = {
-		'unit', 'string', 'player',
+		'unit', 'string;undef', 'player',
 		'known', 'boolean', false,
 	},
 	ret = function(args)
@@ -166,7 +166,7 @@ DogTag:AddTag("Unit", "PercentHP", {
 	end,
 	fakeAlias = "[CurHP / MaxHP * 100]:Round(1)",
 	arg = {
-		'unit', 'string', 'player',
+		'unit', 'string;undef', 'player'
 	},
 	ret = "number",
 	events = "UNIT_HEALTH#$unit;UNIT_MAXHEALTH#$unit",
@@ -178,7 +178,7 @@ DogTag:AddTag("Unit", "PercentHP", {
 DogTag:AddTag("Unit", "MissingHP", {
 	alias = [=[MaxHP(unit=unit, known=known) - HP(unit=unit, known=known)]=],
 	arg = {
-		'unit', 'string', 'player',
+		'unit', 'string;undef', 'player',
 		'known', 'boolean', false,
 	},
 	ret = "number",
@@ -190,7 +190,7 @@ DogTag:AddTag("Unit", "MissingHP", {
 DogTag:AddTag("Unit", "FractionalHP", {
 	alias = [=[Concatenate(HP(unit=unit, known=known), "/", MaxHP(unit=unit, known=known))]=],
 	arg = {
-		'unit', 'string', 'player',
+		'unit', 'string;undef', 'player',
 		'known', 'boolean', false,
 	},
 	ret = "string",
@@ -204,7 +204,7 @@ DogTag:AddTag("Unit", "IsMaxHP", {
 		return UnitHealth(unit) == UnitHealthMax(unit)
 	end,
 	arg = {
-		'unit', 'string', 'player',
+		'unit', 'string;undef', 'player'
 	},
 	ret = "boolean",
 	doc = L["Return True if unit is at full health"],
@@ -250,7 +250,7 @@ DogTag:AddTag("Unit", "HPColor", {
 	end,
 	arg = {
 		'value', 'string;undef', "@undef",
-		'unit', 'string', 'player',
+		'unit', 'string;undef', 'player'
 	},
 	ret = "string",
 	events = "UNIT_HEALTH#$unit;UNIT_MAXHEALTH#$unit",
diff --git a/Categories/Power.lua b/Categories/Power.lua
index b202ca9..2bae778 100644
--- a/Categories/Power.lua
+++ b/Categories/Power.lua
@@ -12,7 +12,7 @@ local L = DogTag_Unit.L
 DogTag:AddTag("Unit", "MP", {
 	code = UnitMana,
 	arg = {
-		'unit', 'string', 'player',
+		'unit', 'string;undef', 'player'
 	},
 	ret = "number",
 	events = "UNIT_MANA#$unit;UNIT_RAGE#$unit;UNIT_FOCUS#$unit;UNIT_ENERGY#$unit;UNIT_MAXMANA#$unit;UNIT_MAXRAGE#$unit;UNIT_MAXFOCUS#$unit;UNIT_MAXENERGY#$unit;UNIT_DISPLAYPOWER#$unit",
@@ -24,7 +24,7 @@ DogTag:AddTag("Unit", "MP", {
 DogTag:AddTag("Unit", "MaxMP", {
 	code = UnitManaMax,
 	arg = {
-		'unit', 'string', 'player',
+		'unit', 'string;undef', 'player'
 	},
 	ret = "number",
 	events = "UNIT_MANA#$unit;UNIT_RAGE#$unit;UNIT_FOCUS#$unit;UNIT_ENERGY#$unit;UNIT_MAXMANA#$unit;UNIT_MAXRAGE#$unit;UNIT_MAXFOCUS#$unit;UNIT_MAXENERGY#$unit;UNIT_DISPLAYPOWER#$unit",
@@ -36,7 +36,7 @@ DogTag:AddTag("Unit", "MaxMP", {
 DogTag:AddTag("Unit", "PercentMP", {
 	alias = "[MP(unit=unit) / MaxMP(unit=unit) * 100]:Round(1)",
 	arg = {
-		'unit', 'string', 'player',
+		'unit', 'string;undef', 'player'
 	},
 	doc = L["Return the percentage mana/rage/energy of unit"],
 	example = '[PercentMP] => "63.2"; [PercentMP:Percent] => "63.2%"',
@@ -46,7 +46,7 @@ DogTag:AddTag("Unit", "PercentMP", {
 DogTag:AddTag("Unit", "MissingMP", {
 	alias = "MaxMP(unit=unit) - MP(unit=unit)",
 	arg = {
-		'unit', 'string', 'player',
+		'unit', 'string;undef', 'player'
 	},
 	doc = L["Return the missing mana/rage/energy of unit"],
 	example = ('[MissingMP] => "%d"'):format(UnitManaMax("player")*.368),
@@ -56,7 +56,7 @@ DogTag:AddTag("Unit", "MissingMP", {
 DogTag:AddTag("Unit", "FractionalMP", {
 	alias = "Concatenate(MP(unit=unit), '/', MaxMP(unit=unit))",
 	arg = {
-		'unit', 'string', 'player',
+		'unit', 'string;undef', 'player'
 	},
 	doc = L["Return the current and maximum mana/rage/energy of unit"],
 	example = ('[FractionalMP] => "%d/%d"'):format(UnitManaMax("player")*.632, UnitManaMax("player")),
@@ -77,7 +77,7 @@ DogTag:AddTag("Unit", "TypePower", {
 		end
 	end,
 	arg = {
-		'unit', 'string', 'player',
+		'unit', 'string;undef', 'player'
 	},
 	ret = "string",
 	events = "UNIT_DISPLAYPOWER#$unit",
@@ -90,7 +90,7 @@ DogTag:AddTag("Unit", "IsPowerType", {
 	alias = [=[Boolean(TypePower(unit=unit) = type)]=],
 	arg = {
 		'type', 'string', '@req',
-		'unit', 'string', 'player',
+		'unit', 'string;undef', 'player'
 	},
 	ret = "boolean",
 	events = "UNIT_DISPLAYPOWER#$unit",
@@ -102,7 +102,7 @@ DogTag:AddTag("Unit", "IsPowerType", {
 DogTag:AddTag("Unit", "IsRage", {
 	alias = ("IsPowerType(type=%q, unit=unit)"):format(L["Rage"]),
 	arg = {
-		'unit', 'string', 'player',
+		'unit', 'string;undef', 'player'
 	},
 	doc = L["Return True if unit currently uses rage"],
 	example = ('[IsRage] => %q; [IsRage] => ""'):format(L["True"]),
@@ -112,7 +112,7 @@ DogTag:AddTag("Unit", "IsRage", {
 DogTag:AddTag("Unit", "IsFocus", {
 	alias = ("IsPowerType(type=%q, unit=unit)"):format(L["Focus"]),
 	arg = {
-		'unit', 'string', 'player',
+		'unit', 'string;undef', 'player'
 	},
 	doc = L["Return True if unit currently uses focus"],
 	example = ('[IsFocus] => %q; [IsFocus] => ""'):format(L["True"]),
@@ -122,7 +122,7 @@ DogTag:AddTag("Unit", "IsFocus", {
 DogTag:AddTag("Unit", "IsEnergy", {
 	alias = ("IsPowerType(type=%q, unit=unit)"):format(L["Energy"]),
 	arg = {
-		'unit', 'string', 'player',
+		'unit', 'string;undef', 'player'
 	},
 	doc = L["Return True if unit currently uses energy"],
 	example = ('[IsEnergy] => %q; [IsEnergy] => ""'):format(L["True"]),
@@ -132,7 +132,7 @@ DogTag:AddTag("Unit", "IsEnergy", {
 DogTag:AddTag("Unit", "IsMana", {
 	alias = ("IsPowerType(type=%q, unit=unit)"):format(L["Mana"]),
 	arg = {
-		'unit', 'string', 'player',
+		'unit', 'string;undef', 'player'
 	},
 	doc = L["Return True if unit currently uses mana"],
 	example = ('[IsMana] => %q; [IsMana] => ""'):format(L["True"]),
@@ -142,7 +142,7 @@ DogTag:AddTag("Unit", "IsMana", {
 DogTag:AddTag("Unit", "IsMaxMP", {
 	alias = "Boolean(MP(unit=unit) = MaxMP(unit=unit))",
 	arg = {
-		'unit', 'string', 'player',
+		'unit', 'string;undef', 'player'
 	},
 	doc = L["Return True if unit is at full rage/mana/energy"],
 	example = ('[IsMaxMP] => %q; [IsMaxMP] => ""'):format(L["True"]),
@@ -152,7 +152,7 @@ DogTag:AddTag("Unit", "IsMaxMP", {
 DogTag:AddTag("Unit", "HasMP", {
 	alias = "Boolean(MaxMP(unit=unit) > 0)",
 	arg = {
-		'unit', 'string', 'player',
+		'unit', 'string;undef', 'player'
 	},
 	doc = L["Return True if unit has no power type at all"],
 	example = ('[HasNoMP] => %q; [HasNoMP] => ""'):format(L["True"]),
@@ -182,7 +182,7 @@ DogTag:AddTag("Unit", "PowerColor", {
 	end,
 	arg = {
 		'value', 'string;undef', '@undef',
-		'unit', 'string', 'player',
+		'unit', 'string;undef', 'player'
 	},
 	ret = "string",
 	events = "UNIT_DISPLAYPOWER#$unit",
diff --git a/Categories/Range.lua b/Categories/Range.lua
index b0cffa3..a8167d4 100644
--- a/Categories/Range.lua
+++ b/Categories/Range.lua
@@ -25,7 +25,7 @@ end)
 DogTag:AddTag("Unit", "Range", {
 	alias = [=[IsVisible(unit=unit) & ~DeadType(unit=unit) ? MinRange(unit=unit) (Concatenate(" - ", MaxRange(unit=unit)) || "+")]=],
 	arg = {
-		'unit', 'string', 'player',
+		'unit', 'string;undef', 'player'
 	},
 	doc = L["Return the approximate range of unit, if RangeCheck-1.0 is available"],
 	example = '[Range] => "5 - 15"; [Range] => "30+"; [Range] => ""',
@@ -38,7 +38,7 @@ DogTag:AddTag("Unit", "MinRange", {
 	end,
 	dynamicCode = true,
 	arg = {
-		'unit', 'string', 'player',
+		'unit', 'string;undef', 'player'
 	},
 	ret = function()
 		if not RangeCheckLib then
@@ -65,7 +65,7 @@ DogTag:AddTag("Unit", "MaxRange", {
 	end,
 	dynamicCode = true,
 	arg = {
-		'unit', 'string', 'player',
+		'unit', 'string;undef', 'player'
 	},
 	ret = function()
 		if not RangeCheckLib then
diff --git a/Categories/Status.lua b/Categories/Status.lua
index 43edb77..ca52335 100644
--- a/Categories/Status.lua
+++ b/Categories/Status.lua
@@ -136,7 +136,7 @@ DogTag:AddTag("Unit", "OfflineDuration", {
 		end
 	end,
 	arg = {
-		'unit', 'string', 'player',
+		'unit', 'string;undef', 'player'
 	},
 	ret = "number;nil",
 	events = "OfflineDuration#$unit",
@@ -162,7 +162,7 @@ DogTag:AddTag("Unit", "DeadDuration", {
 		end
 	end,
 	arg = {
-		'unit', 'string', 'player',
+		'unit', 'string;undef', 'player'
 	},
 	ret = "number;nil",
 	events = "DeadDuration#$unit",
@@ -182,7 +182,7 @@ DogTag:AddTag("Unit", "DeadType", {
 		end
 	end,
 	arg = {
-		'unit', 'string', 'player',
+		'unit', 'string;undef', 'player'
 	},
 	ret = "string;nil",
 	events = "DeadDuration#$unit",
@@ -194,7 +194,7 @@ DogTag:AddTag("Unit", "DeadType", {
 DogTag:AddTag("Unit", "Dead", {
 	alias = "DeadType(unit=unit) Concatenate(' ', DeadDuration(unit=unit):FormatDuration:Paren)",
 	arg = {
-		'unit', 'string', 'player',
+		'unit', 'string;undef', 'player'
 	},
 	doc = L["Return Dead or Ghost and the duration dead if unit is dead"],
 	example = ('[Dead] => "%s (1:34)"; [Dead] => "%s"; [Dead] => ""'):format(L["Dead"], L["Ghost"]),
@@ -211,7 +211,7 @@ DogTag:AddTag("Unit", "AFKDuration", {
 		end
 	end,
 	arg = {
-		'unit', 'string', 'player',
+		'unit', 'string;undef', 'player'
 	},
 	ret = "number;nil",
 	events = "AFKDuration#$unit",
@@ -236,7 +236,7 @@ DogTag:AddTag("Unit", "DND", {
 		end
 	end,
 	arg = {
-		'unit', 'string', 'player',
+		'unit', 'string;undef', 'player'
 	},
 	ret = "string;nil",
 	events = "PLAYER_FLAGS_CHANGED#$unit",
@@ -256,7 +256,7 @@ DogTag:AddTag("Unit", "PvP", {
 		end
 	end,
 	arg = {
-		'unit', 'string', 'player',
+		'unit', 'string;undef', 'player'
 	},
 	ret = "string;nil",
 	doc = L["Return PvP or FFA if the unit is PvP-enabled"],
@@ -276,7 +276,7 @@ DogTag:AddTag("Unit", "IsResting", {
 DogTag:AddTag("Unit", "IsLeader", {
 	code = UnitIsPartyLeader,
 	arg = {
-		'unit', 'string', 'player',
+		'unit', 'string;undef', 'player'
 	},
 	ret = "boolean",
 	doc = L["Return True if unit is a party leader"],
@@ -287,7 +287,7 @@ DogTag:AddTag("Unit", "IsLeader", {
 DogTag:AddTag("Unit", "IsFeignedDeath", {
 	code = UnitIsFeignDeath,
 	arg = {
-		'unit', 'string', 'player',
+		'unit', 'string;undef', 'player'
 	},
 	ret = "boolean",
 	doc = L["Return True if unit is feigning death"],
@@ -343,7 +343,7 @@ DogTag:AddTag("Unit", "HappyIcon", {
 DogTag:AddTag("Unit", "IsTappedByMe", {
 	code = UnitIsTappedByPlayer,
 	arg = {
-		'unit', 'string', 'player',
+		'unit', 'string;undef', 'player'
 	},
 	ret = "boolean",
 	events = "Update",
@@ -357,7 +357,7 @@ DogTag:AddTag("Unit", "IsTapped", {
 		return UnitIsTapped(unit) and not UnitIsTappedByPlayer(unit)
 	end,
 	arg = {
-		'unit', 'string', 'player',
+		'unit', 'string;undef', 'player'
 	},
 	ret = "boolean",
 	events = "Update",
@@ -369,7 +369,7 @@ DogTag:AddTag("Unit", "IsTapped", {
 DogTag:AddTag("Unit", "InCombat", {
 	code = UnitAffectingCombat,
 	arg = {
-		'unit', 'string', 'player',
+		'unit', 'string;undef', 'player'
 	},
 	ret = "boolean",
 	events = "Update",
@@ -393,7 +393,7 @@ DogTag:AddTag("Unit", "FKey", {
 		return nil
 	end,
 	arg = {
-		'unit', 'string', 'player',
+		'unit', 'string;undef', 'player'
 	},
 	ret = "string;nil",
 	doc = L["Return the function key to press to select unit"],
@@ -416,7 +416,7 @@ DogTag:AddTag("Unit", "RaidGroup", {
 		return nil
 	end,
 	arg = {
-		'unit', 'string', 'player',
+		'unit', 'string;undef', 'player'
 	},
 	ret = "number;nil",
 	doc = L["Return the raid group that unit is in"],
@@ -439,7 +439,7 @@ DogTag:AddTag("Unit", "IsMasterLooter", {
 		return false
 	end,
 	arg = {
-		'unit', 'string', 'player',
+		'unit', 'string;undef', 'player'
 	},
 	ret = "boolean",
 	doc = L["Return True if unit is the master looter for your raid"],
@@ -456,7 +456,7 @@ DogTag:AddTag("Unit", "Target", {
 		end
 	end,
 	arg = {
-		'unit', 'string', 'player',
+		'unit', 'string;undef', 'player'
 	},
 	ret = "string",
 	doc = L["Return the unit id of unit's target"],
@@ -477,7 +477,7 @@ DogTag:AddTag("Unit", "Pet", {
 		end
 	end,
 	arg = {
-		'unit', 'string', 'player',
+		'unit', 'string;undef', 'player'
 	},
 	ret = "string;nil",
 	doc = L["Return the unit id of unit's pet"],
@@ -496,7 +496,7 @@ DogTag:AddTag("Unit", "NumTargeting", {
 		return num
 	end,
 	arg = {
-		'unit', 'string', 'player',
+		'unit', 'string;undef', 'player'
 	},
 	ret = "number",
 	events = "UNIT_TARGET;Update",
@@ -522,7 +522,7 @@ DogTag:AddTag("Unit", "TargetingList", {
 		return s
 	end,
 	arg = {
-		'unit', 'string', 'player',
+		'unit', 'string;undef', 'player'
 	},
 	ret = "string;nil",
 	events = "UNIT_TARGET;Update",
@@ -545,7 +545,7 @@ DogTag:AddTag("Unit", "IsUnit", {
 	code = UnitIsUnit,
 	arg = {
 		'other', 'string', '@req',
-		'unit', 'string', 'player',
+		'unit', 'string;undef', 'player'
 	},
 	ret = "boolean",
 	events = "UNIT_FACTION#$unit",
@@ -557,7 +557,7 @@ DogTag:AddTag("Unit", "IsUnit", {
 DogTag:AddTag("Unit", "IsCharmed", {
 	code = UnitIsCharmed,
 	arg = {
-		'unit', 'string', 'player',
+		'unit', 'string;undef', 'player'
 	},
 	ret = "boolean",
 	events = "UNIT_FACTION#$unit",
@@ -569,7 +569,7 @@ DogTag:AddTag("Unit", "IsCharmed", {
 DogTag:AddTag("Unit", "IsVisible", {
 	code = UnitIsVisible,
 	arg = {
-		'unit', 'string', 'player',
+		'unit', 'string;undef', 'player'
 	},
 	ret = "boolean",
 	events = "UNIT_PORTRAIT_UPDATE",
@@ -599,7 +599,7 @@ DogTag:AddTag("Unit", "StatusColor", {
 	end,
 	arg = {
 		'value', 'string;undef', '@undef',
-		'unit', 'string', 'player',
+		'unit', 'string;undef', 'player'
 	},
 	ret = "string;nil",
 	events = "DeadDuration#$unit",
@@ -643,7 +643,7 @@ local DIVINE_INTERVENTION = GetSpellInfo(19752)
 DogTag:AddTag("Unit", "Status", {
 	alias = ("Offline(unit=unit) or (HasDivineIntervention(unit=unit) ? %q) or (IsFeignedDeath(unit=unit) ? %q) or [if Dead(unit=unit) then ((HasSoulstone(unit=unit) ? %q) or Dead(unit=unit))]"):format(DIVINE_INTERVENTION, L["Feigned Death"], L["Soulstoned"]),
 	arg = {
-		'unit', 'string', 'player',
+		'unit', 'string;undef', 'player'
 	},
 	doc = L["Return whether unit is offline, has divine intervention, is dead, feigning death, or has a soulstone while dead"],
 	example = ('[Status] => "Offline"; [Status] => "Dead"; [Status] => ""'),
diff --git a/Categories/Talent.lua b/Categories/Talent.lua
index 444cd95..c0a21de 100644
--- a/Categories/Talent.lua
+++ b/Categories/Talent.lua
@@ -102,7 +102,7 @@ DogTag:AddTag("Unit", "TalentSpec", {
 	end,
 	dynamicCode = true,
 	arg = {
-		'unit', 'string', 'player',
+		'unit', 'string;undef', 'player'
 	},
 	ret = "string;nil",
 	events = "Talent",
@@ -117,7 +117,7 @@ DogTag:AddTag("Unit", "TalentTree", {
 	end,
 	dynamicCode = true,
 	arg = {
-		'unit', 'string', 'player',
+		'unit', 'string;undef', 'player'
 	},
 	ret = "string;nil",
 	events = "Talent",
diff --git a/Categories/Threat.lua b/Categories/Threat.lua
index 01f12f2..32c79a9 100644
--- a/Categories/Threat.lua
+++ b/Categories/Threat.lua
@@ -67,7 +67,7 @@ DogTag:AddTag("Unit", "Threat", {
 	end,
 	dynamicCode = true,
 	arg = {
-		'unit', 'string', 'player',
+		'unit', 'string;undef', 'player'
 	},
 	ret = function()
 		if ThreatLib then
@@ -88,7 +88,7 @@ DogTag:AddTag("Unit", "MaxThreat", {
 	end,
 	dynamicCode = true,
 	arg = {
-		'unit', 'string', 'player',
+		'unit', 'string;undef', 'player'
 	},
 	ret = function()
 		if ThreatLib then
@@ -106,7 +106,7 @@ DogTag:AddTag("Unit", "MaxThreat", {
 DogTag:AddTag("Unit", "PercentThreat", {
 	alias = [=[(Threat(unit=unit) / MaxThreat(unit=unit) * 100):Round(1)]=],
 	arg = {
-		'unit', 'string', 'player',
+		'unit', 'string;undef', 'player'
 	},
 	doc = L["Return the percentage threat that you have against enemy unit or that friendly unit has against your target, if ThreatLib is available"],
 	example = '[PercentThreat] => "62.5"; [PercentThreat:Percent] => "62.5%"',
@@ -117,7 +117,7 @@ DogTag:AddTag("Unit", "PercentThreat", {
 DogTag:AddTag("Unit", "MissingThreat", {
 	alias = "MaxThreat(unit=unit) - Threat(unit=unit)",
 	arg = {
-		'unit', 'string', 'player',
+		'unit', 'string;undef', 'player'
 	},
 	doc = L["Return the missing threat that you have against enemy unit or that friendly unit has against your target, if ThreatLib is available"],
 	example = '[MissingThreat] => "30"',
@@ -127,7 +127,7 @@ DogTag:AddTag("Unit", "MissingThreat", {
 DogTag:AddTag("Unit", "FractionalThreat", {
 	alias = "Concatenate(Threat(unit=unit), '/', MaxThreat(unit=unit))",
 	arg = {
-		'unit', 'string', 'player',
+		'unit', 'string;undef', 'player'
 	},
 	doc = L["Return the current and maximum threat that you have against enemy unit or that friendly unit has against your target, if ThreatLib is available"],
 	example = '[FractionalThreat] => "50/80"',
@@ -140,7 +140,7 @@ DogTag:AddTag("Unit", "HasThreat", {
 	end,
 	dynamicCode = true,
 	arg = {
-		'unit', 'string', 'player',
+		'unit', 'string;undef', 'player'
 	},
 	ret = "boolean",
 	events = "Threat#$unit",
diff --git a/Categories/TooltipScanning.lua b/Categories/TooltipScanning.lua
index 10194a8..e5b1580 100644
--- a/Categories/TooltipScanning.lua
+++ b/Categories/TooltipScanning.lua
@@ -120,7 +120,7 @@ DogTag:AddTag("Unit", "Guild", {
 		end
 	end,
 	arg = {
-		'unit', 'string', 'player',
+		'unit', 'string;undef', 'player'
 	},
 	ret = "string;nil",
 	doc = L["Return the guild name or title of unit"],
@@ -153,7 +153,7 @@ DogTag:AddTag("Unit", "Owner", {
 		return nil
 	end,
 	arg = {
-		'unit', 'string', 'player',
+		'unit', 'string;undef', 'player'
 	},
 	ret = "string;nil",
 	doc = L["Return the name of the owner of unit, if a pet"],
@@ -164,7 +164,7 @@ DogTag:AddTag("Unit", "Owner", {
 DogTag:AddTag("Unit", "Faction", {
 	code = FigureFaction,
 	arg = {
-		'unit', 'string', 'player',
+		'unit', 'string;undef', 'player'
 	},
 	ret = "string;nil",
 	events = "UNIT_FACTION",
@@ -176,7 +176,7 @@ DogTag:AddTag("Unit", "Faction", {
 DogTag:AddTag("Unit", "Zone", {
 	code = FigureZone,
 	arg = {
-		'unit', 'string', 'player',
+		'unit', 'string;undef', 'player'
 	},
 	ret = "string;nil",
 	events = "SlowUpdate",
diff --git a/LibDogTag-Unit-3.0.lua b/LibDogTag-Unit-3.0.lua
index 7ed96e8..ad0164d 100644
--- a/LibDogTag-Unit-3.0.lua
+++ b/LibDogTag-Unit-3.0.lua
@@ -216,7 +216,9 @@ DogTag:AddCompilationStep("Unit", "tag", function(ast, t, tag, tagData, kwargs,
 				t[#t+1] = "\n"
 			end
 		else
-			t[#t+1] = [=[if not DogTag.IsLegitimateUnit[]=]
+			t[#t+1] = [=[if ]=]
+			t[#t+1] = compiledKwargs["unit"][1]
+			t[#t+1] = [=[ and not DogTag.IsLegitimateUnit[]=]
 			t[#t+1] = compiledKwargs["unit"][1]
 			t[#t+1] = [=[] then]=]
 			t[#t+1] = "\n"
@@ -260,7 +262,9 @@ end)
 
 DogTag:AddCompilationStep("Unit", "tagevents", function(ast, t, u, tag, tagData, kwargs, extraKwargs, compiledKwargs, events, returns)
 	if compiledKwargs["unit"] and kwargs["unit"] ~= extraKwargs and kwargs["unit"] ~= "player" then
-		t[#t+1] = [=[if UnitExists(]=]
+		t[#t+1] = [=[if ]=]
+		t[#t+1] = compiledKwargs["unit"][1]
+		t[#t+1] = [=[ and UnitExists(]=]
 		t[#t+1] = compiledKwargs["unit"][1]
 		t[#t+1] = [=[) then]=]
 		t[#t+1] = "\n"
diff --git a/test.lua b/test.lua
index b0aa499..cd091b8 100644
--- a/test.lua
+++ b/test.lua
@@ -433,6 +433,7 @@ MyValue_data = "fakeunit"
 assert_equal(DogTag:Evaluate("[HP(MyValue)]", "Unit"), 'Bad unit: "fakeunit"')
 MyValue_data = 50
 assert_equal(DogTag:Evaluate("[HP(MyValue)]", "Unit"), 'Bad unit: "50"')
+assert_equal(DogTag:Evaluate("[HP(nil)]", "Unit"), nil)
 MyValue_data = nil
 assert_equal(DogTag:Evaluate("[HP(MyValue)]", "Unit"), nil)