Skyrim Mod:Mod File Format/PACK

PACK records describe AI packages, which are used to control the behavior and activities of NPCs.

PACK records use a moderately complex structure, with various fields that occur multiple times and have different meanings depending upon where they occur within the overall structure. The records also seem to generally contain a large amount of unnecessary and/or obsolete content -- deleted activities never seem to actually be deleted from the game data; some sections are required even though they are entirely empty in 99.9% of the PACK records. As a result, a large fraction of the data in a given PACK record may not be visible in the CK editor.

Header

These fields are always found at the start of the PACK record.

C	SubRecord	Name	Type/Size	Info
+	EDID	editorId	zstring	Editor id
-	VMAD	script info	VMAD	script info
*	CTDA	conditions	struct[32]	Conditions controlling when the package can be active. CTDA fields can also be found in the Procedure Tree section of the record, in which case the conditions are specific to that branch of the procedure tree.
*	CIS1	Variable name?	zstring	Auxiliary data for CTDA.
*	CIS2	Variable name?	zstring	Auxiliary data for CTDA.
-	IDLC	Idle Count	uint8	Number of formids found in subsequent IDLA field
-	IDLA	Idle	formid[IDLC]	1 or more IDLE formids
-	IDLF	Idle Flags	uint8	Flags: 0x01: If set: Run In Sequence. If not set: Random 0x04: Do Once 0x08: Unknown
-	IDLT	Idle Time	float
-	QNAM	Owner Quest	formid	QNAM can only appear once in the header section. However, it can also appear in the Begin/End/Change section, with a different format and meaning.
+	PKCU	PKCU field	struct[12]
		Unknown	ulong	Unknown, possibly flags. Values range from 1 to 34.
		Package Template	formid	Formid for another PACK record that is used as a template. This value can only be provided in records that are identified with Package Type "Package", and only templates with type "Package Template" are valid entries.
		Unknown	ulong	Unknown, possibly flags. Values range from 0 to 29.
+	PKDT	Package Flags	struct[12]
		Misc Flags	uint32	Only flags that have a visible effect in the CK are listed here. Many other flags may be set in the game data, but they are probably hold-overs from Oblivion that were phased out during development. 0x04 = Must Complete 0x08 = Maintain Speed at Goal 0x40 = At Package Start Unlock Doors 0x80 = On Package Change Unlock Doors 0x400 = Once Per Day 0x2000 = Preferred Speed (although choice of Walk/Fast Walk/Jog/Run is stored separately, see below) 0x20000 = Always Sneak 0x40000 = Allow Swimming 0x100000 = Ignore Combat 0x200000 = Weapons Unequipped 0x800000 = Weapon Drawn 0x8000000 = No Combat Alert 0x20000000 = Wear Sleep Outfit
		Package Type	uint8	Only the first bit is relevant: 0x01 = Package Template (if not set, type is "Package") 0x12 is always set.
		Interrupt Override	uint8	Only observed values are 0 (None) and 4 (Combat)
		Preferred Speed	uint8	This value is only relevant if the Preferred Speed Misc Flag is set (0x2000 above) 0 = Walk 1 = Jog 2 = Run 3 = Fast Walk
		Unknown	uint8	Possibly padding
		Interrupt Flags	uint32	0x01 = Hellos to player 0x02 = Random conversations 0x04 = Observe combat behavior 0x08 = Greet corpse behavior 0x10 = Reaction to player actions 0x20 = Friendly fire comments 0x40 = Aggro Radius Behavior 0x80 = Allow Idle Chatter 0x200 = World Interactions The remainder of the bits (0xFC00) can also be set, but they appear to be "extra" interrupt flags: the "Set all interrupt flags" sets the flags to 0xFFFF, and "Clear all interrupt flags" sets them to 0x0000, but the higher bits do not correspond to any displayed flags in the CK editor.
+	PSDT	Schedule	struct[12]	Information on when package is allowed to be active
		Month	byte	Any=-1 (only value currently being used in Skyrim)
		Day of week	byte	Day of week -1=Any 0=Sundas 1=Morndas 2=Tirdas 3=Middas 4=Turdas 5=Fredas 6=Loredas 7=Weekdays: MTMTF 8=Weekends: Loredas, Sundas 9=Morndas, Middas, Fredas 10=Tirdas, Turdas
		Date	byte	Date (day of month); Any=0
		Hour	byte	Start hour (0-23); Any=-1
		Minute	byte	Start minutes (0-59); Any=-1
		Unknown	byte[3]	Probably unused padding (although values are typically not zero)
		Duration	uint32	Duration in minutes, although the value is displayed in the CK using decimal hours

Public Package Data

The section providing the public package data is located after the fields listed for the header, and extends until an XNAM field is encountered. It provides a list of activities and parameters controlling those activities, all of which are listed in the "Public Package Data" section of the CK edit interface.

The section is made up of a series of ANAM fields, each of which is followed by various other fields providing the activity parameters corresponding to that ANAM field. Then the section contains a series of UNAM fields, each of which provides the activity name corresponding to one of the previous ANAM fields.

Note that ANAM fields are also found in the Procedure Tree section, if one exists.

C	SubRecord	Name	Type/Size	Info
*	ANAM	Activity Type	zstring	A string identifying the type of data stored in this activity entry. Each ANAM field is followed by one field that provides data with the given type. Possible values in this section, and the associated field, are: Bool: CNAM field, CNAM type=uint8 Float: CNAM field, CNAM type=float Int: CNAM field, CNAM type=int32 Location: PLDT field ObjectList: CNAM field, CNAM type=float SingleRef: PTDA field TargetSelector: PTDA field Topic: PDTO field or TPIC field (only one instance of a TPIC field) One and only one of the following fields is found after each ANAM field. (Other values for ANAM are only found in the Procedure Tree section of the record.)
-	CNAM	Numeric Value	variable	CNAM is 1-4 bytes in size, and the type of data in CNAM depends upon the previous ANAM field; see above.
-	PDTO	Topic Value	struct[8]	Note that PDTO fields can also occur in the Begin/End/Change section
		Type	long	0 = Dialogue 1 = Topic Subtype
		Topic Value	formid/char[4]	Formid for a DIAL record when type=0; 4-character string for type=1 (e.g. "HELO" for "Hello" subtype)
-	PLDT	Location Value	struct[12]
		Type	long	0=Near reference, Location=formid 1=In cell, Location=formid 2=Near package start location, Location=unused 3=Near editor location, Location=unused 6=Near linked reference, Location=formid of a KYWD record 8=Alias (reference), Location=uint32 providing an AliasID 9=Alias (location), Location=formid 12=Near Self, Location=unused
		Location	variable	Location; always 4 bytes in length, but format depends upon Type as listed above. If Location is unused, then value is empty.
		Radius	long	Radius
-	PTDA	Target Value	struct[12]
		Type	long	0=Specific reference, Target=formid 1=Object ID, Target=formid 2=Object Type, Target=uint32 3=Linked Reference, Target=formid 4=Ref Alias, Target=uint32 providing an AliasID 6=Self, Target=unused
		Target	formid/long	Target; always 4 bytes in length, but format depends upon Type as listed above. If Location is unused, then value is empty. For Object Type, number appears to be a lookup value. Known values are: 11 = Weapons: Any
		Count	long	Count (0 in all Skyrim records)
-	TPIC	Unknown	formid	DIAL record
*	UNAM	Activity ID	uint8	Each UNAM field provides a numerical ID; that ID can be looked up in the Package Template to determine the Name of the activity as listed in the CK. Although the UNAM fields are listed after all of the ANAM fields for this section, each UNAM field provides the name for one of the previous ANAM fields. The first UNAM field corresponds to the first ANAM field, etc.
+	XNAM	Unknown	int8	Number ranging from -77 to 99. There is always one XNAM field in a PACK record, and it is always located at the end of the Public Package Data section.

Procedure Tree

This section is the first of two sections that are only found in template packages. This section defines the structure of the procedure tree used by this template and all packages based upon this template.

As with the Public Package Data section, this section is also made up of a series of ANAM fields. However, a completely different set of ANAM values appear in this section, and each ANAM section contains multiple fields, all of which are different than those found in Public Package Data.

This section ends when a UNAM field is found, signaling the start of the Procedure Data section.

C	SubRecord	Name	Type/Size	Info
*	ANAM	Branch Type	zstring	A string identifying the type of branch data stored in the following section. Possible values found in this section are: Procedure: Basic element of the tree (only non-branch element). All individual activities (PKC2 fields) are contained with Procedures. Random: Top-level branch that can contain multiple Procedures. Sequence: Top-level branch that can contain multiple Procedures. Simultaneous: Top-level branch that can contain multiple Procedures. Stacked: Top-level branch that can contain multiple Procedures. Each ANAM entry is followed by multiple fields. The count column for the following entries is relative to a given ANAM field -- overall these fields can always occur 0 or many times in a given record.
+	CITC	Condition Count	uint32	Number of conditions (CTDA fields) in this branch. Can be 0, in which case there are no CTDA fields.
*	CTDA	Conditions	struct[32]	Conditions controlling when this branch can be active. Note that conditions relevant to the overall package are provided using CTDA fields that appear in the header section.
-	PRCB	Unknown	struct[8]	Appears to be two uint32 values
-	PNAM	Procedure Type	zstring	Note that PNAM fields also appear in the Procedure Data Section, in which case formats other than zstring are possible
-	FNAM	Flag	uint32	Flag. Only one bit is in use: 0x01=Success Completes Package
*	PKC2	Activity ID	uint8	The PKC2 fields provide a list of all the activity IDs found in this branch. Note that a given activity ID can occur multiple times within the Procedure Tree Section, in particular if that activity is part of multiple branches.
-	PFO2	Unknown	struct[16]
-	PFOR	Unknown	struct[12]

Procedure Data

This section is also only found in template packages. It provides the name associated with each activity ID. It consists of a series of UNAM fields, each followed by one BNAM field and one PNAM field.

C	SubRecord	Name	Type/Size	Info
*	UNAM	Activity ID	uint8	This is the same activity ID provided in both the Public Package Data and Procedure Tree sections. However, many additional activity IDs can also possibly appear; any additional IDs correspond to activities that were deleted from the package and are no longer accessible through the CK edit interface.
+	BNAM	Activity Name	zstring	The activity name as displayed in the CK
+	PNAM	Unknown	uint32	Probably a flag: only values are 0 or 1. Note that the PNAM fields also appear in the Procedure Tree section, but have a completely different format and meaning.

Begin/End/Change

This section provides the 'On Begin', 'On End', and 'On Change' actions for this package. It is always present at the end of all PACK records (for both standard packages and template packages -- even though the CK editor does not display this section for template packages).

It consists of three marker fields (POBA, POEA, POCA), each of which is always followed by an INAM and a PDTO field. Each marker may also be followed by an old scripting (SCHR) field.

C	SubRecord	Name	Type/Size	Info
+	POBA or	On Begin	0-size	Marks start of 'On Begin' actions
	POEA or	On End	0-size	Marks start of 'On End' actions
	POCA	On Change	0-size	Marks start of 'On Change' actions
+	INAM	Idle	formid	IDLE record. Field is always present but its value is 0 if there is no idle action.
-	SCHR	Old Script	SCHR	Old scripting field.
-	TNAM	Unknown	int32	Seen only on a single PACK record ("Say" / 0x0001CB6) - always 0.
+	PDTO	Topic	struct[8]	Field is always present but is entirely 0 if there is no topic. Note that PDTO fields also appear in Public Package Data section; the same structure is probably used in both cases.