I found what I believe to be a bug or at least an instance of non-compliance with the icalendar specification. I'm using the latest full version. I'm doing a network calendar (using WebDAV).
rfc2445 in section 4.1 defines a line ending (CRLF) as a carriage return and a line feed:
CR = %x0D
; carriage return
LF = %x0A
; line feed
CRLF = CR LF
; Internet standard newline
It appears that when I save an event or todo in rainlendar, it leaves the CRLF on the BEGIN:* and END:* lines but removes the carriage return character from all other lines.
This causes icalendar files created with Rainlendar to fail when they are accessed by the OSX ical application. It does not fail when I use Mozilla Sunbird.
Workaround: It appears that Mozilla Sunbird will parse rainlendar created ics file and will reformat them properly if you edit an event in Sunbird.
If necessary, I can supply example ics files to demonstrate. Let me know if you need this.