Skyrim Mod:Mod File Format/CTDA Field

CTDA fields are widely used in Skyrim records to provide conditions that must be met. The format is similar to that used in Oblivion records, although there are more function indices.

In Skyrim.esm, the following types have CTDA fields: ALCH, COBJ, CPTH, ENCH, FACT, IDLE, INFO, LSCR, MESG, MGEF, MUST, PACK, PERK, QUST, SCEN, SCRL, SMBN, SMQN, SNDR, SPEL.

Related Fields

CTDA fields are often accompanied by several fields.

• CITC (uint32) is sometimes used as a 'Condition Item Count', or a count of CTDA fields. Only certain specific cases make use of a CITC field — but in those cases, the CITC field is required, even if there are no CTDA fields (in which case CITC is 0). Therefore, occurrences of CITC fields correlate poorly with occurrences of CTDA fields.
  • Seen in types: FACT, PACK (only for procedure-specific conditions, not for overall package conditions), SMBN, SMQN, SMEN (always zero, so there are no CTDA fields), MUST

• CIS1 (zstring) variable name, trails CTDA that uses it, replaces 1st argument in function call (value for param1 is very high, unknown if significant or arbitrary)
  • Seen in types: IDLE, PACK, CPTH.

• CIS2 (zstring) variable name, trails CTDA that uses it, replaces 2nd argument in function call (value for param2 is very high, unknown if significant or arbitrary)
  • Seen in types: FACT, ENCH, SPEL, COBJ, QUST, IDLE, PACK, LSCR, PERK, SMBN, SMQN, SCEN, INFO.

Field Layout

The condition is assembled into a statement of the format:

<Reference>.<Function>(<Param1>, <Param2>) <Operator> <Value>

For example,

PlayerRef.GetDistance(MQ304AlduinHideInMistSouthMarker) > 6500

(Where formids have been translated into EditorIDs to make the statement more intelligible)

Name	Type/Size	Info
operator	uint8	Condition type where the upper 3 bits contain the compare operator and the lower 5 bits contain flags. Compare operator (upper 3 bits) 0=Equal to 1=Not equal to 2=Greater than 3=Greater than or equal to 4=Less than 5=Less than or equal to Flags (lower 5 bits) 0x01=OR (default is to AND conditions together) 0x02=Parameters (use aliases) : Force function parameters that usually use REFR forms to use a quest's reference alias instead (exclusive with "use pack data") 0x04=Use global 0x08=Use Pack Data : Force function parameters that usually use REFR forms to use pack data instead (exclusive with "use aliases") 0x10=Swap Subject and Target?
unknown	uint8[3]	Unused data?
ComparisonValue	formid/float	Value against which the function result is compared or a GLOB formid if the UseGlobal flag is set
FunctionIndex	uint16	Function index. See Functions for a list of function indices. Most of the Oblivion indices are still valid, but hundreds of new functions have been added. The value in this field is the index given on the above page, minus 4096.
padding	uint8[2]	Padding (may be non-zero, but the bytes are unused)
All Functions Except GetEventData
param1	formID/int32	First parameter. This can be a number or a Form ID depending on the function; zero if no parameters needed. Note that if param1 is a string type then there will be a CIS1 subrecord following the CTDA with the string.
param2	formID/int32	Second parameter. This can be a number of a Form ID depending on the function; zero if second parameter is not needed. Note that if param2 is a string type then there will be a CIS2 subrecord following the CTDA with the string.
GetEventData
param1	uint16	Event Function. (Enumeration - specifics still need to be documented.)
param2	char[2]	Event Member. (See below.)
param3	formID	Third parameter.
RunOnType	uint32	How to apply the condition 0 = Subject 1 = Target 2 = Reference (see next field) 3 = Combat Target 4 = Linked Reference: Use a reference linked to another reference 5 = Quest Alias: Use quest alias data 6 = Package Data: 7 = Event Data: Use radiant event data
reference	formID	Function reference. For example, if the function is "isDead", the function is applied to the object in the function reference. Zero if no reference needed.
unknown	int32	The index of the package data or quest alias to run on. -1 means "none" and is also used for other run-on types.

Event Member

Codes for each event member depend on the event type. Note that some event types are not used, but are present in the game code.

Event Type	Code	Value
Actor Dialogue Event	L1	Location
	R1	Actor 1
	R2	Actor 2
Actor Hello Event	L1	Location
	R1	Actor 1
	R2	Actor 2
Arrest Event	R1	ArestingGuard [sic]
	R2	Criminal
	L1	Location
	V1	iCrimeType
Assault Actor Event	R1	Victim
	R2	Attacker
	L1	Location
	V1	Crime
Bribe	R1	Actor
	V1	Gold Value
Cast Magic Event	R1	CastingActor
	R2	SpellTarget
	L1	Location
	F1	SpellForm
Change Location Event	R1	Actor
	L1	Old Location
	L2	New Location
Change Relationship Rank	R1	NPC 1
	R2	NPC 2
	V1	Old Relationship
	V2	New Relationship
Craft Item	R1	Workbench
	L1	BenchLocation
	O1	CreatedObject
Crime Gold Event	R1	Victim
	R2	Criminal
	F1	Crime Faction
	V1	Gold Value
	V2	iCrimeType
Dead Body	R1	Actor
	R2	Dead Actor
	L1	Location
Escape Jail	L1	Location
	F1	pCrimeGroup
Flatter	R1	Actor
Increase Level	V1	New Level
Intimidate	R1	Actor
Jail Event	R1	hGuard
	F1	pCrimeGroup
	L1	Location
	V1	Crime Gold
Kill Actor Event	R1	Victim
	R2	Killer
	L1	Location
	V1	Crime Status
	V2	Relationship Rank to Killer before Death
Lock Pick	R1	Actor
	R2	Lock Object
New Voice Power	R1	Actor
	F1	Voice Power
Pay Fine Event	R1	hCriminal
	R2	hGuard
	F1	pCrimeGroup
	V1	Crime Gold
Player Activate Actor	L1	Location
	R1	Actor (one extra space is present after name)
Player Add Item	R1	OwnerRef
	R2	OriginalContainer
	L1	Location
	F1	ObjectForm
	V1	AquireType [sic]
Player Cured	F1	Infection
Player Infected	R1	Transmitting Actor
	F1	Infection
Player Recieves [sic] Favor	R1	Actor
Player Remove Item	R1	OwnerRef
	R2	ItemRef
	L1	Location
	F1	ObjectForm
	V1	RemoveType
Quest Start	Q1	Quest
Script Event	K1	Keyword
	L1	Location
	R1	Ref 1
	R2	Ref 2
	V1	Value 1
	V2	Value 2
Served Time	L1	Location
	F1	pCrimeGroup
	V1	Crime Gold
	V2	Days Jail
Skill Increase	V1	Skill
Trespass Actor Event	R1	Victim
	R2	Trespasser
	L1	Location
	V1	Crime

Notes

• See this forum post for some good details on this subrecord.