Category Archives: Ical RFC5545 / 2445

Notes on working with the icalendar spec:
(RFC2445 spec is obsolete)
More readable format here using old spec:

TZID’s with quotes around them

Some ics files (eg: a zimbra file)  I have encountered have the TZID enclosed in quotes.


The usual use (google calendar etc) is:


The spec examples do not show quotes and the quotes in the terminology definition are not I think meant to be included in the data.  However this is relatively easy to deal with, so the next version of the plugin > 2.9.4 will cope with these.

Please note that the plugin currently ignores the VTIMEZONE in the ics file and uses the php database timezone.

The plugin will also not cope with the following yet (I have not yet encountered an ics file with it’s own timezone identifiers yet!):

fictitious globally unique time zone identifier example:


Ical Calendar to html options

Some considerations in choosing a plugin or script to import one or more shared calendar ical feeds:

  • Completeness and/or robustness of ical implementation? vs type of dates expected by your application. A complete implementation may of necessity be more complex than a simple one. If your dates are simple, may be a simple solution is the answer. Or do you need to allow for all the variations of recurring specifications?
  • Does it cater for all the fields you need? (attendees etc….)
  • Box Calendar or List of Events (Agenda Style)
  • Verbose or concise text (eg: Mo, Tu vs Monday, Tuesday)
  • Explanatory Text options to change?
  • Hardcoded english? or are there language translation options?
  • Possibilities for css styling – does the html code produced allow adequate styling opportunities?
  • Caching? If you have a high volume site, or you want the calendar or agenda in your sidebar, then you need to cache the ics file to avoid placing too much of a load on the server that is hosting the ics file (and slowing down your site)
  • Can it handle or combine multiple calendars?
  • Will it repeat the recurring events per day? or does it note the fact that they repeat on the first day or the current day?


WordPress Ical (ics file) import options:

These are ‘old’ – please see



  • This one looks good, not a full implementation of the code, but the code that is there is well structured, allowing for additional implementation in a clean fashion. Provides a cache. No language translation and alternative css and html options are possible, but not that obvious or easy until you dig into the code. One calendar at a time.