Used with Time to define a
timeperiod. Where Time refers to
the start of the timeperiod, use Base to define the
length of the timeperiod, in exact months (eg
1,3,5,6,12,18), or to specifically define the end of the
timeperiod (eg 15/5/2006).
Base can be one of three
things:
- A length of a timeperiod in
months.
- The date of the end of the
timeperiod eg 1 Jul 2004.
- The date of the end of the
timeperiod as a decimal year, eg 2004.50.
The Finish Date of the timeperiod
If you use this variable to specify the end of the
timeperiod, you may wonder, in the above example, whether
the timeperiod finishes at the start of theday specified,
in this case 1st July, or the end of that day. In BF (and
Excel) a date always expresses the very first instant of
that day, so in this case the timeperiod finishes with
the very last second of June 30. This is in also keeping
with BF"s rule of "include the start date, exclude the
finish date".
How Base adds itself to Time
- When Base adds itself to Time to define a timeperiod, it
retains the day wherever possible. So 15th Jan plus 3
months comes to 15th April.
- When Time is
the last day in the month, the date of the end of the
timeperiod will always come to the end of a month,
irrespective of the days in the month. Therefore 29th
Feb plus 6 months comes to 31st Aug, but 28th Feb plus
6 months comes to 28th Aug.
- By locking onto specific days in the
month, Time and Base are not adhering to a
particular daycount convention, instead they are are
just operating add you would intuitively expect.
|