Sub-year groupings such as seasons, quarters, semesters, etc.

[rybesh]

EDTF Levels 1 and 2 support describing parts of years using concepts outside the standard months and days—concepts such as seasons, quarters, or semesters. EDTF refers to these as “sub-year groupings”.

There is no equivalent in the Time Ontology, thus the draft EDTF Ontology defines classes and properties to enable the creation of datetime descriptions with sub-year parts other than months and days.

edtfo:yearSubdivision is a property analogous the other Time Ontology properties for specifying the parts of a datetime description: it specifies a particular subdivision of a year.

The domain of edtfo:yearSubdivision is edtfo:SubYearDateTimeDescription, a subclass of time:DateTimeDescription which adds the further constraint that such descriptions can have at most one edtfo:yearSubdivision value.

The range of edtfo:yearSubdivision is edtfo:YearSubdivision, which has the subclasses edtfo:Season, edtfo:Quarter, edtfo:Quadrimester, and edtfo:Semestral. Finally, there are a number of named individual instances of these classes that correspond to the various parts of the year (names of seasons, specific quarters, etc.) for which EDTF defines symbols.

The Time Ontology defines a time:unitType property that is used to specify the precision of a datetime description. It takes values that are instances of time:TemporalUnit. The Time Ontology defined named instances of time:TemporalUnit for standard units such as year and month. The draft EDTF Ontology also specifies four named instances of time:TemporalUnit that can be used to specify the precision of datetime descriptions as values of time:unitType:

• edtfo:unitSeason
• edtfo:unitQuarter
• edtfo:unitQuadrimester
• edtfo:unitSemestral

Examples of sub-year grouping descriptions:

• level-1/season.ttl
• level-2/quarter.ttl