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A classification of emissions by emitting activity or economic sector.




Property Type Definition
articleList Collection A list of academic articles cited in the definition of the SourceCategory.
childList Collection For SourceCategory objects that are organized in a tree structure, a list of child SourceCategory objects that take the SourceCategory as their parent.
citation Text  
dataProvider Person or Organization A person or organization responsible for maintaining information about the SourceCategory.
description Text A description of the SourceCategory.
effect Text The atmospheric effect of the SourceCategory: sink, source, reservoir.
emissionMetricList Collection A list of emission metrics classified as belonging to this SourceCategory.
guidanceDocument GuidanceDocument The guidance document in which the SourceCategory was defined.  This object references the publisher, version number, and date of publication of the GuidanceDocument.
inventoryList Collection A list of inventories that use the SourceCategory to classify emissions.
isSink Boolean  
isSource Boolean  
keywordList Collection A list of keywords associated with this SourceCategory.
level Integer For SourceCategory objects that are organized into a tree structure, the level of the SourceCategory within the tree structure as defined by its parent framework. 
parent SourceCategory For SourceCategory objects that are organized in a tree structure, the parent SourceCategory.
sourceType Text The type of emissions source, as defined by the US NEI: biogenic, event, non point, non road, on road, or point.
title Text The name or title of the SourceCategory.
url Url The url of the authoritative description of the SourceCategory.

Key Relationships

SourceCategory (0..*)

Each SourceCategory object may have a single parent SourceCategory, and multiple child SourceCategory objects.  This recursive structure allows source categories to be represented in a tree format, as many guidance documents represent them.

GuidanceDocument (1)

Each SourceCategory object has parent GuidanceDocument, representing the authoritative document that defined the SourceCategory.

ScholarlyArticle (0..*)

A SourceCategory object may relate to many ScholarlyArticle objects, each representing an academic article or other documentation cited in the definition of the SourceCategory.

Inventory (0..*)

A SourceCategory object may be reused by multiple inventories.  The one-to-many relationship between an Inventory object and SourceCategory objects defines the sectoral coverage of the Inventory.

EmissionMetric (0..*)

A SourceCategory will relate to one or more EmissionMetric objects.  A SourceCategory may relate to both atomic EmissionMetric objects, which represent emissions as reported at the most atomic grain within an Inventory, additive EmissionMetric objects, which represent total emissions within a set boundary, and/or empty EmissionMetric objects, which represent the application of a specific EstimationMethodology to SourceCategory within an Inventory without reporting the resulting emissions metric.


Like EstimationMethodology, EmissionFactor, and Fuel objects, SourceCategory objects are drawn from authoritative frameworks published by international organizations or federal environmental agencies, contain no data that is inventory specific, and may be reused by multiple inventories.

Based on the structure of its parent Framework, a SourceCategory object may have a parent SourceCategory and multiple child SourceCategory objects.  For instance, the IPCC organizes source categories into a tree structure.

The SourceCategory object contains properties that describe the source category and its publication, properties that facilitate the comparison of similar source categories, and surrogate key properties that capture source categories that have been “cross-walked” by their publisher to match similar source categories published by other frameworks.

Descriptive properties include name, code, description, framework, url, parent, and level.  Descriptive properties designed to facilitate comparison include sourceType and naicsCode.  Surrogate key properties include canEtCode, emepCode, unIpccCode, usSccCode, and usSitModuleCode.

Researchers will be able to rely on three techniques for discovering similar SourceCategory objects published by different frameworks:

  • use descriptive properties designed to facilitate comparison,
  • use surrogate keys, and
  • find SourceCategories that link to the same or similar EmissionMethodology and EmissionFactor objects.