Next meeting is 19 July. Certainty and Wikidata

[Karl Grossner]

Hello all

The next meeting of this working group is Tuesday, 19 July, at 16.00 CET, 15.00 UK time, 10.00 US Eastern time, etc.

The link to join is https://pitt.zoom.us/j/93496830115

As per our last meeting, I am proposing additions to the format based on suggestions from group members. These will be voted on afterwards, with a web form so all can vote, whether they attend this meeting or not.

For the group's consideration at the upcoming meeting, there are two spec change items: adding a certainty attribute for time, and adding "wd" as a namespace prefix for Wikidata in the LP format context like so:

   "wd": "http://www.wikidata.org/entity/"

I've created a new GitHub issue, https://github.com/LinkedPasts/linked-places-format/issues/47. Another agenda topic should be where to maintain conversations like this. For the time being, including here as well...

best
Karl

Existing situation

Currently, geometry in Linked Places format (LPF) has a "certainty" attribute, which allows one of three values, "certain", "less-certain", and "uncertain" (see B below for reference). This convention is the same as used in the Pleiades place model. Certainty was not included in the "when" object used to describe temporality, an oversight.

Note that the term "attribute" is synonymous with "property" and "relation." The "certainty" attribute can optionally apply to a single geometry element or to a geometry within a GeometryCollection.

It has been proposed to support the "certainty" attribute in the "when" element, wherever it is used, as illustrated in A. Note that it could be applied to any individual timespan or named period assertion.

Implications:
Software that fully supports LPF will faithfully store, and/or render, and/or make available, entire records. It *should* do something to display each record's contents, including visually differentiating elements that have associated "certainty" attributes. Certainty is always optional so its absence should never cause validation to fail.

A. WHEN
1. Applying to entire when object
"when": {
  "timespans": [
    { "start": { "in": "yyyy-mm" },
      "end": {
          "earliest": "-yyyy",
          "latest": "yyyy-mm-dd" }
    }
  ],
  "periods": [
    { "name": "Anglo-Saxon Period, 449-1066",
      "uri": "http://n2t.net/ark:/99152/p06c6g3whtg" }
  ],
  "label": "for a century during the Anglo-Saxon period",
  "duration": "P100Y"
  "certainty": "less-certain"
}

2. Applying to any individual timespan or period
"when": {
  "timespans": [
    { "start": { "in": "yyyy-mm" },
      "end": {
          "earliest": "-yyyy",
          "latest": "yyyy-mm-dd" },
      "certainty": "less-certain"
    }
  ],
  "periods": [
    { "name": "Anglo-Saxon Period, 449-1066",
      "uri": "http://n2t.net/ark:/99152/p06c6g3whtg",
      "certainty": "certain"
    }
  ],
  "label": "for a century during the Anglo-Saxon period",
  "duration": "P100Y"
}

B. GEOMETRY
1. Single geometry
"geometry": {
    "type": "Point",
    "coordinates": [-1.2879,51.6708],
    "geowkt": "POINT(-1.2879 51.6708)",
    "when": {"timespans":[
        {"start":{"earliest": "1600"},"end":{"in":"1699"}}
    ]},
    "certainty": "less-certain"
}

2. Geometry collection
"geometry": {
  "type": "GeometryCollection",
  "geometries": [
      { "type": "Point",
        "coordinates": [-1.2879,51.6708],
        "geowkt": "POINT(-1.2879 51.6708)",
        "when": {"timespans":[
            {"start":{"earliest": "1600"},"end":{"in":"1699"}}
        ]},
        "certainty": "less-certain"
      },
      { "geowkt": "POLYGON ((-1.3077 51.6542, -1.2555 51.6542,
            -1.2555 51.6908, -1.3077 51.6908, -1.3077 51.6542))",
        "when": {"timespans":[{"start":"1700"}]},
        "certainty": "certain"
      }
  ]
}