Periods of time

The last section described date or time point value representation principles. Periods of time can be modeled by two time points, expressing the beginning and end points of the validity, represented in different ways, delimiting whether the time point is exclusive or inclusive. The second principle is associated with just one attribute, commonly pointing to the beginning point, followed by the time interval duration (period). There are several designations to represent particular values. The general format for the period is P[n]Y[n]M[n]DT[n]H[n]M[n]S, where [n] is replaced by the numerical value of the physical element. P, Y, M, D, T, H, M, and S are the delimiters for individual element reflection, signifying the following:

• P expresses the period:
  • Y: Number of years
  • M: Number of months
  • D: Number of days
• T refers to the time components:
  • H: The hour value
  • M: The minute value
  • S: The second value

As stated, a common representation of periods is formed by the...