TimeOriginTimeOrigin
-
The zero point for TimeFrame axis values
- Description:
- This specifies the origin from which all time values are measured.
The default value (zero) results in the TimeFrameTimeFrame describing
absolute time values in the system given by the SystemSystem attribute
(e.g. MJD, Julian epoch, etc). If a TimeFrame is to be used to
describe elapsed time since some origin, the TimeOrigin attribute
should be set to hold the required origin value. The TimeOrigin value
stored inside the TimeFrame structure is modified whenever TimeFrame
attribute values are changed so that it refers to the original moment
in time.
- Type:
- Floating point.
- Class Applicability:
-
TimeFrame
-
All TimeFrames have this attribute.
-
Input Formats
- The formats accepted when setting a TimeOrigin value are listed
below. They are all case-insensitive and are generally tolerant
of extra white space and alternative field delimiters:
- Besselian EpochEpoch: Expressed in decimal years, with or without
decimal places ("B1950" or "B1976.13" for example).
- Julian Epoch: Expressed in decimal years, with or without
decimal places ("J2000" or "J2100.9" for example).
- Units: An unqualified decimal value is interpreted as a value in
the system specified by the TimeFrame's System attribute, in the
units given by the TimeFrame's Unit attribute. Alternatively, an
appropriate unit string can be appended to the end of the floating
point value ("123.4 d" for example), in which case the supplied value
is scaled into the units specified by the Unit attribute.
- Julian Date: With or without decimal places ("JD 2454321.9" for
example).
- Modified Julian Date: With or without decimal places
("MJD 54321.4" for example).
- Gregorian Calendar Date: With the month expressed either as an
integer or a 3-character abbreviation, and with optional decimal
places to represent a fraction of a day ("1996-10-2" or
"1996-Oct-2.6" for example). If no fractional part of a day is
given, the time refers to the start of the day (zero hours).
- Gregorian Date and Time: Any calendar date (as above) but with
a fraction of a day expressed as hours, minutes and seconds
("1996-Oct-2 12:13:56.985" for example). The date and time can be
separated by a space or by a "T" (as used by ISO8601 format).
-
Output Format
- When enquiring TimeOrigin values, the returned formatted floating
point value represents a value in the TimeFrame's System, in the unit
specified by the TimeFrame's Unit attribute.