HED specification

Links

• PDF released version (V3.3.0)

• PDF working version

• Specification source

• Stable specification source

• HED resources

• HED homepage

• HED project homepage

Specification role

The HED specification document formalizes the syntax and behavior of HED (Hierarchical Event Descriptors) vocabulary, annotations, and supporting tools. The specification supports three versions of the specification:

• develop - development branch which is under discussion.

• latest - includes revisions approved by the HED Working Group but not released.

• stable - the latest released form.

For more information about HED see The HED project homepage and the HED resources page.

Contents:

• 1. Introduction to HED
  • 1.1. Scope of HED
  • 1.2. Brief history of HED
  • 1.2. Goals of HED
  • 1.3. HED design principles
  • 1.4. Specification organization
• 2. HED terminology
  • 2.1 Definitions
    • Agent [*]
    • Condition-variable [*]
    • Control-variable [*]
    • Dataset
    • Event [*]
    • Event-context [*]
    • Event marker
    • Event-stream [*]
    • Experiment-participant [*]
    • Experimental-trial [*]
    • HED schema [*]
    • HED string
    • HED tag
    • Indicator-variable [*]
    • Parameter [*]
    • Recording [*]
    • Tag-group
    • Task [*]
    • Temporal scope
    • Time-block [*]
  • 2.2 Character sets and restrictions
• 3. HED formats
  • 3.1. Schema formats
    • 3.1.1. Official schema releases
    • 3.1.2. Schema layout overview
      • 3.1.2.1. The header
      • 3.1.2.2. The prologue
      • 3.1.2.3. The schema section
      • 3.1.2.4. Unit classes and units
      • 3.1.2.5. Unit modifiers
      • 3.1.2.6. Value classes
      • 3.1.2.7. Schema attributes
      • 3.1.2.8. Schema properties
      • 3.1.2.9. The epilogue
    • 3.1.3. Naming conventions
      • 3.1.3.1. Node elements
      • 3.1.3.2. Epilogue and prologue
      • 3.1.3.3. Naming in other blocks
    • 3.1.4. MediaWiki schema format
    • 3.1.5. XML schema format
  • 3.2. Annotation formats
    • 3.2.1. Vocabulary organization
    • 3.2.2. Tag forms
    • 3.2.3. Tag case-sensitivity
    • 3.2.4. Tags that take values
    • 3.2.5. Tag extensions
    • 3.2.6. Tag namespace prefixes
    • 3.2.7. Strings and groups
      • 3.2.7.1. Parenthesis and order
      • 3.2.7.2. Tag group attributes
      • 3.2.7.3. Empty tags and groups
      • 3.2.7.4. Repeated expressions
    • 3.2.8. Special tags
      • 3.2.8.1. The Definition tag
      • 3.2.8.2. Def and Def-expand tags
      • 3.2.8.3. Onset, Offset, and Inset
      • 3.2.8.4. Duration and Delay
      • 3.2.8.5. The Event-context tag
    • 3.2.9. Sidecars
      • 3.2.9.1. Sidecar entries
      • 3.2.9.2. Sidecar validation
      • 3.2.9.3. Sidecar curly braces
      • 3.2.9.4. A sidecar example
    • 3.2.10. Tabular files
      • 3.2.10.1 Tabular types
      • 3.2.10.2. Tabular annotations
      • 3.2.10.3. Event-level processing
      • 3.2.10.4. File-level processing
  • 3.3. Semantic versioning
• 4. Basic annotation
  • 4.1. Instantaneous events
  • 4.2. Sensory presentations
  • 4.3. Task role
  • 4.4. Agent actions
  • 4.5. Experimental control
  • 4.6. Data features
  • 4.7. What else?
• 5. Advanced annotation
  • 5.1. Creating definitions
  • 5.2. Using definitions
    • 5.2.1. The Def tag
    • 5.2.2. The Def-expand tag
  • 5.3. Temporal scope
    • 5.3.1. Using Onset and Offset
    • 5.3.2. Using Inset
    • 5.3.3. Using Duration
    • 5.3.4. Using Delay
  • 5.4. Event streams
  • 5.5. Event contexts
  • 5.6. Experimental design
  • 5.7. Specialized annotation
    • 5.7.1. Parameter tags
• 6. Infrastructure and tools
  • 6.1. Basic tag handling
    • 6.1.1. Tag forms
    • 6.1.2. Parentheses and commas
    • 6.1.3. Tag ordering
    • 6.1.4. Definitions
  • 6.2. File-level handling
  • 6.3. HED support of BIDS
    • 6.3.1. BIDS tabular files
    • 6.3.2. BIDS timeseries
    • 6.3.3. BIDS sidecars
    • 6.3.4. Annotation assembly
    • 6.3.5. HED version in BIDS
    • 6.3.6. HED in the BIDS validator
    • 6.3.7. HED python tools
• 7. Library schemas
  • 7.1. Why library schemas?
  • 7.2. Standalone schemas
  • 7.3. Partnered schemas
    • 7.3.1. Partnered files
    • 7.3.2. Partnered formats
    • 7.3.3. Auxiliary sections
    • 7.3.4. Partnered attributes
    • 7.2.5. Motivation for partners
      • 7.3.5.1. Auxiliary consistency
      • 7.3.5.2. Reserved tag handling
      • 7.3.5.3. Annotation conciseness
      • 7.3.5.4. Library searches
      • 7.3.5.5. Suggested tags
      • 7.3.6 Lazy partnering
  • 7.4. Library schema design
    • 7.4.1. General design rules
    • 7.4.2. Standalone design rules
    • 7.4.3. Partnered design rules
    • 7.4.4. Schema namespaces
  • 7.5. Library schemas in BIDS
• 8. The HED ontology
  • 8.1. HED views and representations
    • 8.1.1. The annotator’s view
    • 8.1.2. The ontologist’s view
    • 8.1.3. HED information space
    • 8.1.4. HED representations
      • 8.1.4.1. The MediaWiki format
      • 8.1.4.2. Spreadsheet files
      • 8.1.4.3. Spreadsheet format
      • 8.1.4.4. Spreadsheet <–> MediaWiki
      • 8.1.4.5. Tag spreadsheet <–> Ontology
  • 8.2. HED schema to ontology
    • 8.2.1. Overall ontology structure
    • 8.2.2. HED Tags
      • 8.2.2.1. MediaWiki tag format
      • 8.2.2.2. XML tag format
      • 8.2.2.3. OWL format for HED classes
    • 8.2.3. Schema attributes
      • 8.2.3.1. Attribute ontology types
      • 8.2.3.2. Schema attribute properties
      • 8.2.3.3. Attribute representation
      • 8.2.3.4. MediaWiki attribute format
      • 8.2.3.5. XML attribute format
      • 8.2.3.6. OWL format for attributes.
    • 8.2.4 Other auxiliary sections
  • 8.3. HED global identifiers
    • 8.3.1. Schema identifiers
    • 8.3.2. Ontology namespace
    • 8.3.3. HED IRIs
• A. Schema format details
  • A.1. Auxiliary schema sections
    • A.1.1. Unit classes and units
    • A.1.2. Unit modifiers
    • A.1.3. Value classes
    • A.1.4. Schema attributes
      • A.1.4.1. allowedCharacter
      • A.1.4.2. conversionFactor
      • A.1.4.3. defaultUnits
      • A.1.4.4. deprecatedFrom
      • A.1.4.5. extensionAllowed
      • A.1.4.6. hedId
      • A.1.4.7. inLibrary
      • A.1.4.8. relatedTag
      • A.1.4.9. requireChild
      • A.1.4.10. reserved
      • A.1.4.11. rooted
      • A.1.4.12. SIUnit
      • A.1.4.13. SIUnitModifier
      • A.1.4.14. SIUnitSymbolModifier
      • A.1.4.15. suggestedTag
      • A.1.4.16. tagGroup
      • A.1.4.17. takesValue
      • A.1.4.18. topLevelTagGroup
      • A.1.4.19. unique
      • A.1.4.20. unitClass
      • A.1.4.21. unitPrefix
      • A.1.4.22. unitSymbol
      • A.1.4.23. valueClass
      • A.1.4.x. Deprecated attributes
    • A.1.5. Schema properties
  • A.2. MediaWiki file format
    • A.2.1. Overall file layout
    • A.2.2. MediaWiki header
    • A.2.3. MediaWiki prologue and epilogue
    • A.2.4. MediaWiki schema section
    • A.2.5. MediaWiki auxiliary sections
      • A.2.5.1. Unit classes and units
      • A.2.5.2. Unit modifiers
      • A.2.5.3. Value classes
      • A.2.5.4. Schema attributes
      • A.2.5.5. Schema properties
  • A.3. XML file format
    • A.3.1. XML file layout
    • A.3.2. XML header
    • A.3.3. XML prologue and epilogue
    • A.3.4. XML schema section
    • A.3.5. XML auxiliary sections
      • A.3.5.1. Unit classes
      • A.3.5.2. Unit modifiers
      • A.3.5.3 Value classes
      • A.3.5.4. Schema attributes
      • A.3.5.5. Schema properties
• B. HED errors
  • B.1. HED validation errors
    • CHARACTER_INVALID
    • COMMA_MISSING
    • DEF_EXPAND_INVALID
    • DEF_INVALID
    • DEFINITION_INVALID
    • ELEMENT_DEPRECATED*
    • PARENTHESES_MISMATCH
    • PLACEHOLDER_INVALID
    • REQUIRED_TAG_MISSING
    • SCHEMA_LOAD_FAILED
    • SIDECAR_BRACES_INVALID
    • SIDECAR_INVALID
    • SIDECAR_KEY_MISSING*
    • STYLE_WARNING*
    • TAG_EMPTY
    • TAG_EXPRESSION_REPEATED
    • TAG_EXTENDED*
    • TAG_EXTENSION_INVALID
    • TAG_GROUP_ERROR
    • TAG_INVALID
    • TAG_NAMESPACE_PREFIX_INVALID
    • TAG_NOT_UNIQUE
    • TAG_REQUIRES_CHILD
    • TEMPORAL_TAG_ERROR
    • TILDES_UNSUPPORTED
    • UNITS_INVALID
    • UNITS_MISSING*
    • VALUE_INVALID
    • VERSION_DEPRECATED*
  • B.2. Schema validation errors
    • B.2.1. General validation errors
      • SCHEMA_ATTRIBUTE_INVALID
      • SCHEMA_ATTRIBUTE_VALUE_INVALID
      • SCHEMA_CHARACTER_INVALID
      • SCHEMA_DEPRECATION_ERROR
      • SCHEMA_DUPLICATE_NODE
      • SCHEMA_HEADER_INVALID
      • SCHEMA_LIBRARY_INVALID
      • SCHEMA_SECTION_MISSING
      • SCHEMA_VERSION_INVALID
    • B.2.3. MediaWiki format errors
      • WIKI_DELIMITERS_INVALID
      • WIKI_LINE_START_INVALID
      • WIKI_SEPARATOR_INVALID
    • B.2.4. XML format errors
      • XML_SYNTAX_INVALID
    • B.2.5 Schema loading errors

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