OBO Ontology Editing Guide

OBO Ontology Editing Guide

This skill provides guidance and tools for editing ontologies in OBO format.

Project Layout Conventions

Most OBO ontologies follow a similar structure:

• Main development file is typically src/​ontology/​{ontology}-edit.obo
• Individual terms can be checked out to terms/ directory for editing
• Some projects may have different layouts - check the project's documentation

Querying Ontology Terms

Use the obo-grep.pl script for searching OBO files:

• Look at a specific term by ID:
  • obo-grep.pl --noheader -r 'id: ONTO:0004177' src/​ontology/​{ontology}-edit.obo
• All mentions of an ID:
  • obo-grep.pl --noheader -r 'ONTO:0004177' src/​ontology/​{ontology}-edit.obo
• Search by regex (e.g., all mentions of hand or foot):
  • obo-grep.pl --noheader -r '(hand|foot)' src/​ontology/​{ontology}-edit.obo
• Search is much faster than full file reads
• ONLY search the main edit file (usually src/​ontology/​{ontology}-edit.obo)
• DO NOT do manual greps or read entire files unless necessary

Before Making Edits

• Read the request carefully and make a plan, especially if there is nuance
• If a PMID is mentioned, try to read it using: aurelian fulltext PMID:NNNNNN
• This also works for DOIs and URLs for scientific papers (if accessible)
• ALWAYS check proposed parent terms for consistency
• Check project-specific guidelines if available

Editing Workflow

IMPORTANT: Use Checkout/​Checkin for Large Files

• Do not edit large ontology files directly
• Use the checkout/​checkin workflow for individual terms
• Check out a term: obo-checkout.pl src/​ontology/​{ontology}-edit.obo ONTO:1234567 [OTHER_IDS]
• This creates a single stanza file: terms/​{ontology}_1234567.obo (note: colon replaced with underscore)
• Edit the small file in the terms/ folder
• Check back in: obo-checkin.pl src/​ontology/​{ontology}-edit.obo ONTO:1234567 [OTHER_IDS]
• Checking in updates the edit file and removes the file from terms/
• You can edit multiple terms in one batch file if needed

Scripts Available

This skill includes three essential scripts:

1. obo-grep.pl - Fast searching of OBO files
2. obo-checkout.pl - Extract terms to individual files for editing
3. obo-checkin.pl - Merge edited terms back into main file

All scripts are available in your PATH when this skill is loaded.

OBO Format Guidelines

Basic Structure

• Term ID format: ONTO:NNNNNNN (check project conventions for number of digits)
• Each term requires:
  • id: - unique identifier
  • name: - human-readable label
  • namespace: - ontology namespace
  • def: - definition with references in square brackets
• Use standard relationship types: is_a, part_of, has_part, etc.
• Follow existing term patterns for consistency

Handling New Term Requests (NTRs)

• Check project conventions for temporary ID ranges
• Example: Some projects use ranges like ONTO:777xxxx for new terms
• Always check for ID clashes: grep 'id: ONTO:777' src/​ontology/​{ontology}-edit.obo
• NEVER guess ontology IDs - use search tools to find actual terms
• NEVER guess PMIDs for references - do web searches if needed

Citations and References

• Cite publications appropriately: def: "..." [PMID:nnnn, doi:mmmm]
• Fetch full text when needed: aurelian fulltext <PMID:nnn> (also works with DOIs and URLs)
• All synonyms should include proper citations
• Never use empty brackets [] without a source

Synonyms

Synonyms should include proper attribution:

Correct:

synonym: "alternative name" EXACT [PMID:12345678]
synonym: "abbrev" EXACT ABBREVIATION [PMID:12345678]

Relationships and Logical Definitions

• All terms should have at least one is_a parent
• Logical definitions follow genus-differentia form
• Text definitions should mirror logical definitions
• Include source attribution for relationships when based on literature:

Logical Definitions (intersection_of)

Example of proper intersection_of usage:

[Term]
id: ONTO:0000715
name: specific disease
def: "A general disease that involves specific location." [PMID:12345678]
is_a: ONTO:0001082 ! general disease
intersection_of: ONTO:0004971 ! general disease
intersection_of: disease_has_location UBERON:0000029 ! specific location

Note that in OWL this corresponds to: 'specific disease' EquivalentTo 'general disease' and 'disease has location' some 'specific location'

Obsoleting Terms

• Obsolete terms should have NO logical axioms (is_a, relationship, intersection_of)
• Obsolete terms may have one replaced_by tag (exact replacement)
• Or multiple consider tags (suggested alternatives)
• Always include obsolescence reason and tracker reference

Example of simple obsolescence:

[Term]
id: ONTO:0100334
name: obsolete term name
property_value: IAO:0000231 OMO:0001000
property_value: IAO:0000233 "https://github.com/​{project}/​issues/​XXXX" xsd:anyURI
is_obsolete: true
replaced_by: ONTO:0100321

Example with considerations instead of replacement:

[Term]
id: ONTO:0100229
name: obsolete term name
def: "OBSOLETE. Original definition here." [original references]
property_value: IAO:0000231 OMO:0001000
property_value: IAO:0000233 "https://github.com/​{project}/​issues/​XXXX" xsd:anyURI
is_obsolete: true
consider: ONTO:0100259
consider: ONTO:0100260

Important Notes on Obsolescence

• Synonyms and xrefs can be migrated to replacement terms judiciously
• Never do complete merges with alt_id - use obsolescence with replacement instead
• No relationships should point to an obsolete term
• When obsoleting, you may need to rewire other terms to "skip" the obsoleted term

Metadata Best Practices

• Link to issue trackers: property_value: IAO:0000233 "https://github.com/​{project}/​issues/​XXXX" xsd:anyURI
• Sign new terms (don't tag pre-existing terms):

  property_value: http://purl.org/​dc/​terms/​creator https://orcid.org/​0000-0001-2345-6789
  

• All terms should have definitions with at least one reference (preferably PMID)
• Dates are typically auto-generated by build processes

Syntax Checking

Validate OBO syntax using ROBOT:

robot convert --catalog src/​ontology/​catalog-v001.xml \
  -i src/​ontology/​{ontology}-edit.obo \
  -f obo \
  -o {ontology}-edit.TMP.obo

Use -vvv flag for full stack trace if there are errors.

Design Patterns

Many OBO ontologies use DOSDP (Dead Simple Ontology Design Patterns):

• Check src/​patterns/​dosdp-patterns/​*.yaml for project-specific patterns
• Follow existing patterns when creating similar terms
• Common patterns include:
  • Location-based disease patterns
  • Gene-related disease patterns
  • Part-of hierarchies
  • Abnormality patterns

Important Reminders

• NEVER guess identifiers of any kind
• If you include an identifier not provided by the user, you MUST verify it
• PMIDs can be checked with aurelian or web search
• Always follow project-specific conventions and check existing examples
• When in doubt, ask for clarification rather than making assumptions