Any historian with an interest in any pre-early modern period will not be surprised to hear that the formal structuring of dates presented a challenge, and that the various DDH/KCL prosopographies took somewhat different directions for dealing with dates, based on the views of the historians in the project.
Here we have chosen to provide two approaches to representing dating. One (:DateRangeTEI) includes in FPO an approach to dates which follows that found in the TEI standards, section 13.1. Within the structures proposed here, we support the possible use, as TEI recommends, of the ISO standard for presentation of dates: (ISO 8601). This format is similar (but, unfortunately, not the same) as several of the suggested forms used for CIDOC-CRM’s E50 Date entity. The proposed alternative to :DateRangeTEI (:DateRangeCompound) matches the usage of one of the CCH/DDH prosopographies and allows a still richer expression for a date range.
- :DateRange: This is the class for a time period specified as a date range. Almost all attributes that specify dates in FPO refer to :DateRange rather than simple :Date because often (and for historical periods before the modern era, almost all) dates cannot be tied down to a specific year, but need to be expressed as a range of possible dates.
- :Date: This is the class for a specific date. It provides for day, month and year to be provided, but allows for day and month to be optional, in which case the date is actually, strictly speaking, a date range: all the days in the year.
- :DateRangeTEI: draws on the definition for dates and date ranges provided by TEI P5, section 13.1. It supports two dates which provide a date range based on a starting and ending date. These two dates are, in turn, expressed as :Date objects.
- :DateRangeCompound: provides for a specification of a date range based on the provision of 4 dates, not two. This reflects the fact that dates are often given in terms of events that must bracket the range, and the events themselves are unclearly dated. Thus, a date like:Blessing of Abbot John of Kelso × Death of Bishop William of Morayactually requires four dates because the blessing of the abbot and the death of the bishop are, themselves, unsure. This is often represented by the notation:
date x date – date x date
where the first two values represent the range for the event that defines the earliest possible date, and the second two the event that defines the last possible date. The four date model was used in the PASE project.
The following Properties are defined in FPO for Dates and DateRanges:
- : hasDay, :hasMonth, :hasYear for :Date: provides three numbers that define a particular date. The day and month are optional. All CCH/DDH projects used this numeric mechanism for dates.
- :hasISO8601Date for :Date: provides the date in ISO8601 format (this is provided to support TEI recommendations for the provision of dates.
- :hasTextualDescription for :DateRange: In CCH/DDH projects dating often was a result of a simple deductive process on the part of our researchers. Thus, this property provides a text string in which this deduction can be briefly described. It might, for example, contain a string like “Blessing of Abbot John of Kelso × Death of Bishop William of Moray”. PASE, PoMS, PONE and Charlemagne all provided this mechanism.
The following relationships devined in FPO between date entities and to other entities are described here:
- :isTo, :isFrom, :isNotAfter, :isNotBefore (from :DateRangeTEI to :Date): provides the way to specify the two dates needed to express a date range. The “To”, “From”, “NotAfter” and “NotBefore” varients match the TEI definitions in TEI P5, section 13.1
- :hasFromRange, :hasToRange (from :DateRangeCompound to :DateRangeTEI): provides the way to provide the two start and two end dates needed for :DateRangeCompound.
- :hasLifeDates (from :Person to :DateRange): all of CCH/DDH/KCL’s factoid prosopographies provided a property to contain a person’s life dates. If this attribute is used in a project, it was assumed to occur only once per :Person. For all the CCH/DDH/KCL projects, our historian partners expected to provide at most one set of life dates for each historical person.
- :hasDateAssertionMade (from :Assertion to :DateRange): provides the mechanism for historians to provide a date (or Date Range) when the assertion was made. Note that this is not necessarily the same date associated with the assertion itself. A source by the Venerable Bede, for example, will generate factoids for events that happened before his work was written. In contrast to the dates Bede is talking about, this is the date in which Bede made the assertion, when the assertion was written. This relationship can be simply omitted if the historians are unwilling or unable to provide it. For CCH/DDH prosopographics only one of these links was made, if any were made at all.
- :dateForAssertion (from :StateOfAffairsFactoid to :DateRange): provides the mechanism for specifying a date where the source asserts that something was so: when Alfred was King of England, for example. This date is not the same as the one connected to a factoid through :hasDateAssertionMade, which specifies when the assertion itself was made (probably a date associated with the writing of the source). This relationship can be simply omitted if the historians are unwilling or unable to provide it. For CCH/DDH prosopographies only one of these links was made, if any were made at all.
- :occurredOn (from :EventFactoid to :DateRange): provides the date (or date range) when the source asserted that the event happened. The Battle of Hastings, for example, occurred in 1066. .This relationship can be simply omitted if the historians are unwilling or unable to provide it. For CCH/DDH prosopographies only one of these links was made, if any were made at all.