cdm/src/main/java/ucar/nc2/time/CalendarPeriod.java
public static CalendarPeriod.Field fromUnitString(String udunit) {
    udunit = udunit.trim();
    udunit = udunit.toLowerCase();

    if (udunit.equals("s")) return Field.Second;
    if (udunit.equals("ms")) return Field.Millisec;

      // eliminate plurals
    if (udunit.endsWith("s")) udunit = udunit.substring(0, udunit.length()-1);

    switch (udunit) {
      case "second":
      case "sec":
        return Field.Second;
      case "millisecond":
      case "millisec":
      case "msec":
        return Field.Millisec;
      case "minute":
      case "min":
        return Field.Minute;
      case "hour":
      case "hr":
      case "h":
        return Field.Hour;
      case "day":
      case "d":
        return Field.Day;
      case "month":
      case "mon":
        return Field.Month;
      case "year":
      case "yr":
        return Field.Year;
      default:
        throw new IllegalArgumentException("cant convert " + udunit + " to CalendarPeriod");
    }
  }
public static CalendarPeriod.Field fromUnitString(String udunit) {
    udunit = udunit.trim();
    udunit = udunit.toLowerCase();

    if (udunit.equals("s")) return Field.Second;
    if (udunit.equals("ms")) return Field.Millisec;

      // eliminate plurals
    if (udunit.endsWith("s")) udunit = udunit.substring(0, udunit.length()-1);

    switch (udunit) {
      case "second":
      case "sec":
        return Field.Second;
      case "millisecond":
      case "millisec":
      case "msec":
        return Field.Millisec;
      case "minute":
      case "min":
        return Field.Minute;
      case "hour":
      case "hr":
      case "h":
        return Field.Hour;
      case "day":
      case "d":
        return Field.Day;
      case "month":
      case "mon":
        return Field.Month;
      case "year":
      case "yr":
        return Field.Year;
      default:
        throw new IllegalArgumentException("cant convert " + udunit + " to CalendarPeriod");
    }
  }
Convert a period string into a CalendarPeriod.Field.
@param udunit period string
@return CalendarPeriod.Field enum
@throws IllegalArgumentException if not valid format