Internet DRAFT - draft-douglass-icalendar-fractional-time
draft-douglass-icalendar-fractional-time
Calendaring extensions N. Jenkins
Internet-Draft R. Stepanek
Intended status: Standards Track FastMail
Expires: January 8, 2022 M. Douglass
BCS
July 7, 2021
iCalendar: Representing fractional seconds in iCalendar
draft-douglass-icalendar-fractional-time-00
Abstract
This document defines a way to represent fractional seconds in
iCalendar.
Status of This Memo
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This Internet-Draft will expire on January 8, 2022.
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. New iCalendar parameters . . . . . . . . . . . . . . . . . . 2
2.1. FRACTIONAL parameter . . . . . . . . . . . . . . . . . . 2
3. Obtaining a Property Value . . . . . . . . . . . . . . . . . 3
4. Mapping from iCalendar to JSCalendar . . . . . . . . . . . . 4
5. Mapping from iCalendar to JSCalendar . . . . . . . . . . . . 4
6. Open issues . . . . . . . . . . . . . . . . . . . . . . . . . 5
6.1. Recurrences . . . . . . . . . . . . . . . . . . . . . . . 5
7. Normative References . . . . . . . . . . . . . . . . . . . . 5
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 6
1. Introduction
There has been an expressed need for the ability to use fractional
seconds in iCalendar. With the advent of JSCalendar there is a way
to do so in that representation. This specification provides a -
partially backwards compatible - way to represent such times in
iCalendar.
It is probable that applications needing fractional seconds require
recurrence rules that use sub-second intervals.
This specification also shows how values should be mapped to and from
JSCalendar.
2. New iCalendar parameters
2.1. FRACTIONAL parameter
Parameter name: FRACTIONAL
Purpose: This parameter is used to contain a value with fractional
seconds for time values and durations.
Description: This parameter MAY be specified on properties of type
DATE-TIME or DURATION. It MUST be a valid iCalendar DATE-TIME or
DURATION value with the addition of fractional seconds. The value
MUST NOT be negative for durations but MAY be negative for alarm
triggers.
Applications receiving a property with a FRACTIONAL parameter MUST
ensure its value is consistent with the value of the property.
The property value must match:
- a positive FRACTIONAL value rounded up to the next non-
fractional second or
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- a negative FRACTIONAL value rounded down the next non-fractional
second
If the values do not match the the application MUST assume that
the property value has been updated by an application that is
unaware of the FRACTIONAL parameter. The parameter should be
ignored in this case.
Format Definition:
This parameter is defined by the following notation:
fractional-param = DATE-TIME or DURATION
Example:
DTSTART;FRACTIONAL=20190605T133015.03:20190605T133015
3. Obtaining a Property Value
If the property has a FRACTIONAL parameter first check that it is a
valid value using the criteria specified in Section 2.1. if valid,
use that value for the iCalendar property.
If the property has no FRACTIONAL parameter or the value of that
parameter is invalid then use the normal property value.
For example:
...
ESTIMATED-DURATION;FRACTIONAL="PT17H15M23.5S:PT18H
...
The value here is "PT18H" because the FRACTIONAL parameter is not valid.
...
ESTIMATED-DURATION:PT18H
...
The value here is "PT18H" because there is no FRACTIONAL parameter.
...
ESTIMATED-DURATION;FRACTIONAL="PT17H15M23.5S:PT17H15M24S
...
The value here is "PT17H15M23.5S" because the FRACTIONAL parameter is valid.
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4. Mapping from iCalendar to JSCalendar
When mapping properties possibly containing time, use the iCalendar
property value obtained as specified in Section 3.
For example:
...
ESTIMATED-DURATION;FRACTIONAL="PT17H15M23.5S:PT18H
...
maps to
...
"estimatedDuration": "PT18H"
...
because the FRACTIONAL parameter is not valid..
...
ESTIMATED-DURATION:PT18H
...
maps to
...
"estimatedDuration": "PT18H"
...
and
...
ESTIMATED-DURATION;FRACTIONAL="PT17H15M23.5S:PT17H15M24S
...
maps to
...
"estimatedDuration": "PT17H15M23.5S"
...
because the FRACTIONAL parameter is valid.
5. Mapping from iCalendar to JSCalendar
If the jscalendar property value has fractional seconds then the
[RFC5545] value is set to the jscalendar property value rounded up to
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the next non-fractional value and a FRACTIONAL parameter is added
with the full unrounded value.
For example:
...
"duration": "PT0.5S"
...
maps to
...
DURATION;FRACTIONAL="PT0.5S":PT1S
...
and
...
"duration": "PT1H"
...
maps to
...
DURATION:PT1H
...
6. Open issues
6.1. Recurrences
It is probably the case that subsecond intervals are most useful for
short recurrence intervals. Neither JSCalendar nor iCalendar
currently allows that.
This probably only requires that the interval value be allowed to
contain fractional values (for seconds frequency only?).
7. Normative References
[RFC5545] Desruisseaux, B., Ed., "Internet Calendaring and
Scheduling Core Object Specification (iCalendar)",
RFC 5545, DOI 10.17487/RFC5545, September 2009,
<https://www.rfc-editor.org/info/rfc5545>.
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Authors' Addresses
Neil Jenkins
FastMail
PO Box 234
Collins St West
Melbourne VIC 8007
Australia
Email: neilj@fastmailteam.com
URI: https://www.fastmail.com
Robert Stepanek
FastMail
PO Box 234
Collins St West
Melbourne VIC 8007
Australia
Email: rsto@fastmailteam.com
URI: https://www.fastmail.com
Michael Douglass
Bedework Commercial Services
226 3rd Street
Troy, NY 12180
United States of America
Email: mdouglass@bedework.com
URI: http://bedework.com
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