1. Controlled Vocabularies
Providing context
Controlled Vocabularies
Sean Gaffney
(with acknowledgements to Rob Thomas, BODC)

2. What is a vocabulary?
A person's vocabulary is the set of words within a language that are familiar to that person.
A vocabulary usually develops with age, and serves as a useful and fundamental tool for communication and acquiring knowledge.
(R. Thomas, BODC, September 2016)

3. Why use controlled vocabs?
Divided by a common language
(R. Thomas, BODC, September 2016)

4. Why use controlled vocabs?
Support terms with explicit definitions
Remove ambiguity
Resource for all
Publish on the web
Make the implicit become explicit!
(R. Thomas, BODC, September 2016)

5. MEDIN & Controlled Vocabs
Where do MEDIN use controlled vocabs?
Data Guidelines and Discovery Metadata Standard
How to access the MEDIN vocabularies?

6. Availability through website

7. Vocabularies used by MEDIN

8. NVS2 Vocab Service: Hosted at BODC. Manual search link is:
Uses Simple Knowledge Organization System (SKOS) concepts to build URLs:
Format is:
Example:
Fully computer readable. Output in XML

9. NVS2 Vocabulary client
Instruments, platforms, sea areas, geometries etc

11. Relationships between vocabs

12. MEDIN Keywords Keywords describe certain aspects of your dataset
MEDIN recommends “SeaDataNet Parameter Discovery Vocabulary” – P02
Accessible through NVS2 and SeaDataNet
Two SeaDataNet routes
Access table P02 directly from MEDIN website
Use SeaDataNet hierarchy to do this
P01 route through NVS2

13. SeaDataNet hierarchies
Parameter relationships and discovery
How best to choose your P02 term?

14. P01 route through NVS2

15. This gives you term for measurement

16. Things to be aware of…
Links on MEDIN vocab page bring you to SeaDataNet vocab list page, not to individual vocabs or NVS2.
Searching may not be intuitive – definitions may have text in different orders to what is expected e.g. sea temperature as ‘Temperature of the water column’ not ‘Water column temperature’
Vocabs are no use if not correctly referenced…what is best practice? URIs, term codes, vocabulary full titles, dates etc.
Different vocabs may have similar terms but different use cases. Research which is the right one for your needs.
Unusual terminology

17. How to add? E-mail Sean Gaffney sgaf@bodc.ac.uk
- check with appropriate governance group.

18. Providing context - Coordinate Reference Systems
The data were sampled at ,
The data came from an area 6 miles from the lighthouse, bearing 245 degrees
Data cost money to sample.
Without knowing where and when a measurement or observation occurs they have no value.
Need therefore to be able to provide a trustworthy unambiguous position for samples.
Are the following numbers enough to provide precise positions of sampled data?
The data are from 54 degrees 10’ 45’’ North, 3 degrees 30’ 20’’ West

19. Coordinate Reference Systems
LATITUDE and LONGITUDE are NOT UNIQUE! Coordinates define a position unambiguously only when the reference system that those coordinates are part of has been identified!

20. Coordinate Reference Systems
What is a CRS?
This is a coordinate system which is referenced to the earth based on a datum.
OGP, 2007, Surveying and Positioning Guidance note 1

21. Coordinate Reference Systems
Where is the Eiffel Tower?
Coordinates:
48°51’29’’N, 2°17’40’’E
OGP, 2007, Surveying and Positioning Guidance note 1

22. Implications!
Platform drilling . Meridional grid wrongly applied in directional software. 12 dry wells dug. Loss of capital expenditure of $2 million. Reputation damage. New program of work needed
Construction. Proposed position for new subsea manifold issued on ED50 datum. Contractor assumed positions in WGS-84 and drilled in wrong place. Resulted in fine of $500,000, reputational damage and contract dispute between contract parties

23. Practice
Aim – to familiarise yourself with different controlled vocabularies
Navigate to the MEDIN webpage for controlled vocabularies within
2) Try and locate some suitable MEDIN keywords from P02 using
The NVS 2 service
The link to table P02 in the SeaDataNet List
The P08/theme approach from SeaDataNet
d) Using P01, trying wildcards to see how they are handled in the system
3) How would you reference these keywords?
4) What other vocabularies and terms are of use to your work?
5) Have a search of the EPSG registry and note your impressions – what would you give as a reference for a particular CRS?