Scope note: This class comprises all forms of names or codes, such as historical periods, and dates, which are characteristically used to refer to a specific E52 Time-Span. The instances of E49 Time Appellation may vary in their degree of precision, and they may be relative to other time frames, "Before Christ" for example. Instances of E52 Time-Span are often defined by reference to a cultural period or an event e.g. 'the duration of the Ming Dynasty'. Examples: - "Meiji" [Japanese term for a specific time-span] - "1st half of the XX century" - "Quaternary" - "1215 Hegira" [a date in the Islamic calendar] - "Last century" In First Order Logic: E49(x) ⊃ E41(x)