# LOOT Metadata Syntax

## Contents

1. Introduction
2. Metadata File Contents
3. Data Structures
   1. Tag Data Structure
   2. File Data Structure
   3. Message Data Structure
   4. Location Data Structure
   5. Dirty Info Data Structure
   6. Plugin Data Structure
4. Condition Strings
   1. Functions
   2. The Negator & Junctors
   3. Order Of Evaluation
5. Language Codes
6. License
7. Feature Support

## Introduction

The metadata syntax is what LOOT's masterlists and userlists are written in. If you know YAML, good news: the syntax is essentially just YAML 1.2. If you don't know YAML, then its Wikipedia page is a good introduction. All you really need to know is:

- How lists and associative arrays (key-value maps) are written.
- That whitespace is important, and that only normal spaces (ie. no non-breaking spaces or tabs) count as such.
- That data entries that are siblings must be indented by the same amount, and child data nodes must be indented further than their parents (see the example later in this document if you don't understand).
- That YAML files must be written in a Unicode encoding.
- That each key in a key-value map must only appear once per map object.

Some important points that are more specific to how LOOT uses YAML:

- LOOT's support for YAML syntax is incomplete. A list of known limitations can be found here. The only major missing piece is support for merge keys (`<<:`).
- Strings are case-sensitive, apart from file paths, regular expressions and checksums.

Some properties of file paths as used by LOOT:

- They are evaluated as paths relative to the game's Data folder.
- They cannot reference a path outside of the game's folder structure, ie. they cannot contain the substring `../../`.
- Regular expression file paths must be written in the EMCAScript syntax.
- Only the filename of a regex file path may contain non-literal regex syntax, ie. if the filename part of the regex file path is removed, the remainder must be an exact folder path (though with the regex syntax special characters escaped). For example, given the regex file path `Meshes\\Resources(1|2)\\(upperclass)?table.nif`, LOOT will look for a file named `table.nif` or `upperclasstable.nif` in the `Meshes\Resources(1|2)` folder, rather than looking in the `Meshes\Resources1` and `Meshes\Resources2` folders.

Please test any changes you make before uploading them. One way of doing this is to run LOOT, another is to copy/paste what you've changed into here, though it won't catch condition syntax errors and doesn't use the same parser as LOOT so may give different results.

## Metadata File Contents

The root of a metadata file is a key-value map. LOOT will recognise the following keys, none of which are required:

Key Name | Value Type | Notes
--- | --- | ---
`globals` | message list | A list of message data structures for messages that are displayed independently of any plugin.
`plugins` | plugin list | A list of plugin data structures, holding all the plugin metadata within the file.

Other keys may also be present, but are not processed by LOOT. The message and plugin data structures are detailed in the next section.

An example metadata file: `globals: - type: say content: 'You are using the latest version of LOOT.' condition: 'version("LOOT", "0.5.0.0", ==)' plugins: - name: 'Armamentarium.esm' tag: - Relev - name: 'ArmamentariumFran.esm' tag: - Relev - name: 'Beautiful People 2ch-Ed.esm' tag: - Eyes - Graphics - Hair - R.Relations`

## Data Structures

LOOT expects metadata to be laid out using a certain set of data structures, described in this section.

### Tag Data Structure

LOOT metadata files can contain suggestions for the addition or removal of Bash Tags, and this is the structure used for them. It has two forms: the first is a simple string, and the second is a key-value map. All values in the map are strings.

The simple form: `tag`

where `tag` is the Bash Tag, preceded by a minus sign if it is suggested for removal.

The map form:

Key Name | Required | Notes
--- | --- | ---
`name` | ✓ | A Bash Tag, preceded by a minus sign if it is suggested for removal.
`condition` | ✗ | A condition string that is evaluated to determine whether this Bash Tag should be suggested: if it evaluates to true, the Tag is suggested, otherwise it is ignored. See Condition Strings for details.

Examples: `Relations` or `name: -Relations condition: 'file("Mart''s Monster Mod for OOO.esm") or file("FCOM_Convergence.esm")'`

### File Data Structure

Not to be confused with the structure of the metadata file itself, this structure can be used to hold file paths. It has two forms: the first is a simple string, and the second is a key-value map. All values in the map are strings.

The simple form: `filepath`

where `filepath` is an exact (ie. not regex) file path relative to the game's Data folder.

The map form:

Key Name | Required | Notes
--- | --- | ---
`name` | ✓ | An exact (ie. not regex) file path or name.
`display` | ✗ | A substitute string to be displayed instead of the file path in any generated messages, eg. the name of the mod the file belongs to.
`condition` | ✗ | A condition string that is evaluated to determine whether this file data should be used: if it evaluates to true, the data is used, otherwise it is ignored. See Condition Strings for details.

Examples: `'../obse_loader.exe'` or `name: '../obse_loader.exe' condition: 'version("../obse_loader.exe", "0.0.18.0", >=)' display: 'OBSE v18+'`

### Message Data Structure

Messages are given as key-value maps.

Key Name | Data Type | Required | Notes
--- | --- | --- | ---
`type` | string | ✓ | The type string can be one of three keywords, see the table below for their semantics.
`content` | string or localised content list | ✓ | Either simply a string, or a list of localised content data structures. If the latter, one of the structures must be for English.
`condition` | string | ✗ | A condition string that is evaluated to determine whether the message should be displayed: if it evaluates to true, the message is displayed, otherwise it is not. See Condition Strings for details.
`subs` | list of strings | ✗ | A list of strings to be substituted into the message content string. The content string must use numbered specifiers (`%1%`, `%2%`, etc.), where the numbers correspond to the position of the substitution string in this list to use, to denote where these strings are to be substituted.

There are three message types:

Keyword | Description
--- | ---
`say` | A generic message, useful for miscellaneous notes.
`warn` | A warning message, describing a non-critical issue with the user's mods (eg. dirty mods).
`error` | An error message, decribing a critical installation issue (eg. missing masters, corrupt plugins).

The localised content data structure is a key-value map, with all values being strings:

Key Name | Required | Notes
--- | --- | ---
`str` | ✓ | The actual message content string.
`lang` | ✓ | The language that `str` is written in, given as a POSIX language code. The languages LOOT supports are given in Language Codes.

LOOT supports formatting of messages using GitHub Flavored Markdown. Support is provided by the Marked library (v0.3.2). Strings that get substituted into messages, such as file display names and dirty info utility strings, also support the same formatting options.

LOOT handles messages and languages as follows:

1. If a message's `content` value is a string, the message will use the string as its content if displayed.
2. If a message's `content` value is a list of localised content structures, then the first structure with a language that matches LOOT's current language will be used as the message's content if displayed. If there are no matches, then the first structure in English will be used.

Examples (translations by Google): `type: say condition: 'file("foo.esp")' content: - lang: en str: 'An example link: <http://www.example.com>' - lang: ru str: 'Это пример ссылки: <http://www.example.com>'` would be displayed as

> отмечать: Это пример ссылки: http://www.example.com

if the current language was Russian and `foo.esp` was installed, while `type: say content: 'An alternative [example link](http://www.example.com), with no translations.'` would be displayed as

> отмечать: An alternative example link, with no translations.

In English, `type: say content: 'A newer version of %1% [is available](%2%). subs: - 'this plugin' - 'http://www.example.com'` would be displayed as

> Note: A newer version of this plugin is available.

### Location Data Structure

This data structure is used to hold information on where a plugin is hosted online. It is not currently used by LOOT, but it was suggested that since the LOOT team receives a considerable number of plugin URLs, they should be recorded in a standard format, as there is no existing store of such information and it could prove useful in the future.

The data structure has two forms: the first is a simple string, and the second is a key-value map. The first form should be used for a URL without any associated version data, such as when it is not clear which version is found there, or when it is the only known hosting location for the plugin and as such hosts all available versions. The second form should be used when version data can be associated with the URL, such as when the URL only hosts a subset of the available versions of the plugin.

The simple form: `URL`

where `URL` is a URL at which the plugin may be found.

The map form:

Key Name | Data Type | Required | Notes
--- | --- | --- | ---
`link` | string | ✓ | A URL at which the plugin may be found.
`ver` | string list | ✓ | A list of versions that can be found at the URL.

Examples: `'http://skyrim.nexusmods.com/mods/19/'` or `link: 'http://steamcommunity.com/sharedfiles/filedetails/?id=87144366' ver: - '1.3.2c'`

### Dirty Info Data Structure

This structure holds information on which versions of a plugin are dirty, and how many identical-to-master records, deleted records and deleted navmeshes (if applicable) it contains. Dirty info is given as a key-value map.

Key Name | Data Type | Required | Notes
--- | --- | --- | ---
`crc` | hexadecimal integer | ✓ | The CRC checksum of the dirty plugin, before cleaning. LOOT displays the CRCs of installed plugins in its report. The 8-character CRC should be preceded by `0x` so that it is correctly interpreted.
`util` | string | ✓ | The utility that should be used to clean the plugin.
`itm` | integer | ✗ | The number of identical-to-master records reported for the dirty plugin. If the number is unknown, this field should not be supplied. If the number is known and zero, this field should be supplied.
`udr` | integer | ✗ | The number of undeleted records reported for the dirty plugin. If the number is unknown, this field should not be supplied. If the number is known and zero, this field should be supplied.
`nav` | integer | ✗ | The number of deleted navmeshes reported for the dirty plugin. If the number is unknown, this field should not be supplied. If the number is known and zero, this field should be supplied.

Examples: `crc: 0x3DF62ABC util: '[TES5Edit](http://www.creationkit.com/TES5Edit_Cleaning_Guide_-_TES5Edit)' itm: 4 udr: 160 nav: 0`

### Plugin Data Structure

This is the structure that brings all the others together, and forms the main component of a metadata file. It is a key-value map.

Key Name | Data Type | Required | Notes
--- | --- | --- | ---
`name` | string | ✓ | Can be an exact plugin filename or a regular expression plugin filename. If the period that precedes the file extension has been escaped (eg. `\.esp`, `\.esm`), the string is treated as a regular expression, otherwise it is treated as an exact filename.
`enabled` | boolean | ✗ | Enables or disables use of the plugin object. Used for user rules, but no reason to use it in the masterlist. If unspecified, defaults to `true`.
`priority` | integer | ✗ | Modifies plugin position relative to others that change one or more of the same records, but which are otherwise unrelated (ie. neither plugin lists the other as a master, requirement, or in its `after` list). Plugins that don't change any of the same records are not compared, unless: One of the plugins is a "dummy" plugin, containing only a header record. One of the plugins has a priority greater than or equal to 1,000,000. In this case, only the modulo (ie. remainder when divided) with 1,000,000 is used when comparing plugin priority values – the rest is only used to signify that the plugin should be compared against all others. For example, `priority: 153000352` and `priority: 352` have equal values when compared, but a plugin with the first priority will be compared against all others, while a (non-dummy) plugin with the second priority will be compared against only those it conflicts with. A plugin with a higher priority value will load after a plugin with a lower priority value. Value can be anything in the range `-2000000000` to `2000000000`, and if unspecified defaults to `0`.
`after` | file list | ✗ | An unordered list of plugins that this plugin must load after, but which are not dependencies. Used for resolving specific compatibility issues and by user rules for specifying custom plugin positions.
`req` | file list | ✗ | An unordered list of files that this plugin requires to be present. This plugin will load after any plugins listed. If any of these files are missing, an error message will be displayed. Intended for use specifying implicit dependencies, as LOOT will detect a plugin's explicit masters itself.
`inc` | file list | ✗ | An unordered list of files that this plugin is incompatible with. If any of these files are present, an error message will be displayed.
`msg` | message list | ✗ | The messages attached to this plugin. The messages will be displayed in the order that they are listed.
`tag` | tag list | ✗ | An unordered list of Bash Tags suggested for this plugin. If a Bash Tag is suggested for both addition and removal, the latter will override the former when the list is evaluated.
`url` | location list | ✗ | An unordered list of locations for this plugin. If the same version can be found at multiple locations, only one location should be recorded. This metadata is not currently used by LOOT.
`dirty` | dirty info list | ✗ | An unordered list of dirty info structures for this plugin.

Each plugin must have only one matching non-regex entry. If multiple non-regex entries exist with the same `name` value, all but the first will be ignored. A plugin may match any number of regex entries though, and their metadata will be merged, with later entries being merged into earlier entries as detailed in the table below. Merging only takes place if both entries have their `enabled` value set to `true` (which is the default if unspecified).

Key Name | Merge Behaviour (merging B into A)
--- | ---
`name` | Not merged.
`enabled` | Replaced but must be `true` anyway.
`priority` | Replaced by B's value.
`after` | Merged. If A and B both contain an entry with the same `name` value, B's copy is skipped.
`req` | Merged. If A and B both contain an entry with the same `name` value, B's copy is skipped.
`inc` | Merged. If A and B both contain an entry with the same `name` value, B's copy is skipped.
`msg` | Merged. If A and B both contain an entry with the same content string (if there are multiple content strings, the first is checked), then B's copy is skipped.
`tag` | Merged. If A and B both contain an entry with the same `name` value, B's copy is skipped, unless one is suggesting the tag for addition and the other is suggesting it for removal, in which case both entries are kept.
`url` | Currently skipped by the parser, so neither A nor B will contain any entries anyway.
`dirty` | Merged. If A and B both contain an entry with the same `crc` value, B's copy is skipped.

Example: `name: 'Oscuro''s_Oblivion_Overhaul.esm' req: - 'Oblivion.esm' # Don't do this, Oblivion.esm is a master of Oscuro's_Oblivion_Overhaul.esm, so LOOT already knows it's required. - name: 'example.esp' display: '[Example Mod](http://www.example.com)' condition: 'version("Oscuro''s_Oblivion_Overhaul.esm", "15.0", ==)' tag: - Actors.Spells - Graphics - Invent - Relations - Scripts - Stats - name: -Relations condition: 'file("Mart''s Monster Mod for OOO.esm") or file("FCOM_Convergence.esm")' msg: - type: say content: 'Do not clean. "Dirty" edits are intentional and required for the mod to function.'`

## Condition Strings

Condition strings can be used to ensure that data is only acted on by LOOT under certain circumstances. They are very similar to boolean conditional expressions in programming languages such as Python, though more limited. Their EBNF grammar is: `[ negator ], function, { junctor, [ negator ], function } ;`

The `[ negator ], function` grammar is referred to as a condition, and two conditions joined by an operator, ie. `condition, operator, condition` is referred to as a compound condition.

LOOT caches the results of condition evaluations, so performance is not really an issue. A regular expression check will still take longer than a file check though, so use the former only when appropriate to do so.

### Functions

There are several conditions that can be tested for using the functions detailed in the table below.

Function | Syntax | Description
--- | --- | ---
File | `file("filepath")` | Returns true if filepath is installed, false otherwise.
File | `regex("regex")` | Returns true if a file matching regex is found, false otherwise.
Checksum | `checksum("filepath", checksum)` | Returns true if the calculated checksum of filepath matches checksum, false otherwise. If filepath does not exist, returns false.
Version | `version("filepath", "version", comparator)` | Returns true if the boolean expression `(actual version of filepath) comparator version` holds true, false otherwise. If filepath does not exist and comparator is `==`, `>` or `>=`, returns false. If filepath does not exist and comparator is `!=`, `<` or `<=`, returns true. The comparison is not a straightforward per-character comparison, but instead uses the Alphanum algorithm.
Plugin Active Status | `active("filepath")` | Returns true if filepath is a `.esp` or `.esm` file that is both installed and active, false otherwise.

The different types of variable used in the above functions are described in more detail below.

Variable Type | Description
--- | ---
`filepath` | A Windows file path, or `LOOT`, which references the LOOT executable being run.
`regex` | A regular expression string to match file paths to.
`checksum` | A string of hexadecimal digits representing an unsigned integer that is the data checksum of a file. LOOT displays the checksums of plugins in its user interface after running.
`version` | A string of characters representing the version of a plugin or executable. LOOT displays the versions of plugins in its user interface after running.
`comparator` | A comparison operator, ie. one of `==`, `!=`, `<`, `>`, `<=` or `>=`, meaning "is equal to", "is not equal to", "is less than", "is greater than", "is less than or equal to" and "is greater than or equal to" respectively.

### The Negator & Junctors

The negator, or logical negation operator, inverts the value of the function that follows it. Its inclusion is optional, and its syntax is simply: `not`

Below is a truth table for the negator.

Value of `function` | Value of `not function`
--- | ---
false | true
true | false

There are two supported junctors, the logical conjunction (logical and operator) and the logical disjunction (logical or operator), that operate on the expressions to their left and right.

Junctor | Syntax | Description
--- | --- | ---
Logical Conjunction | `and` | Both conditions must evaluate to true for the compound condition to evaluate to true. If not, the compound condition evaluates to false.
Logical Disjunction | `or` | One condition or both conditions must evaluate to true for the compound condition to evaluate to true. If neither condition is true, then the compound condition evaluates to false.

The following is a truth table for the junctors:

Value of `condition1` | Value of `condition2` | Value of `condition1 and condition2` | Value of `condition1 or condition2`
--- | --- | --- | ---
true | true | true | true
true | false | false | true
false | true | false | true
false | false | false | false

### Order Of Evaluation

When a condition string is evaluated, its constituent parts are evaluated according to the standard precedence rules of operator logic, ie.

1. Function
2. Negator
3. Logical and
4. Logical or

Below is a table that lists some combinations of conditions, showing for each the order of evaluation by explicit bracketing. To make it easier to read, the `negator function` pair is shortened to `C` after the first example.

String Structure | Evaluated As
--- | ---
`negator function` | `( negator ( function ) )`
`C and C` | `( C and C )`
`C or C` | `( C or C )`
`C and C and C` | `( ( C and C ) and C )`
`C or C or C` | `( ( C or C ) or C )`
`C and C or C` | `( ( C and C ) or C )`
`C or C and C` | `( C or ( C and C ) )`
`C and C and C and C` | `( ( ( C and C ) and C ) and C )`
`C and C and C or C` | `( ( ( C and C ) and C ) or C )`
`C and C or C and C` | `( ( C and C ) or ( C and C ) )`
`C and C or C or C` | `( ( ( C and C ) or C ) or C)`
`C or C or C or C` | `( ( ( C or C ) or C ) or C )`
`C or C or C and C` | `( ( C or C ) or ( C and C ) )`
`C or C and C or C` | `( ( C or ( C and C ) ) or C )`
`C or C and C and C` | `( C or ( ( C and C ) and C ) )`

You can also explicitly enclose any condition in brackets to override the evaluation order, eg. `C and ( C or C )` is evaluated as `C and ( C or C )`, in contrast to the unbracketed string above.

## Language Codes

LOOT supports the following languages and language codes:

Language | POSIX Code
--- | ---
Chinese | zh_CN
English | en
Finnish | fi
French | fr
Polish | pl
Brazilian Portuguese | pt_BR
Russian | ru
Spanish | es
German | de
Danish | da

## License

This document is part of the LOOT documentation.
Copyright (C) 2012—2014 WrinklyNinja
See the file LOOT ReadMe.html for copying conditions.

## Feature Support

Different versions of LOOT may have varying levels of support for the syntax detailed in this document. Such variation in support is detailed in the table below. Unless otherwise noted, all syntax changes are backwards-compatible (ie. you can use the features without breaking the masterlist for users on older versions).

| LOOT Version
--- | ---
Feature | <= 0.6 | 0.7
GitHub Flavored Markdown message formatting | Only URL hyperlinking is supported, for `file:`, `http:` and `https:` URLs, using the `[label](url)` and `<url>` syntaxes. | LOOT uses the Marked library (v0.3.2) to provide support for most of GitHub Flavored Markdown, minus the GitHub-specific features (like @mentions, issue/repo linking and emoji).
Message string substitution (ie. `sub:`) | Not supported. | Support planned, but not yet implemented in the latest alpha release.
YAML merge keys (ie. `<<:`) | Not supported. | Support planned, but not yet implemented in the latest alpha release.