I want to forward an appointment over the internet so that person can add it
to their calendar.  

I created an appointment and forwarded it as an iCalendar – thinking the
process would work in a similar way to forwarding a contact as vCard.  
However, it didn’t.  

When the recipient opens the attachment it looks more like a meeting request
than an appointment except that the Accept / Reject buttons are greyed out.  

They couldn’t add it to their calendar by using Save and Close (there was no
Save and Close button).  Nor could they drag it to the Calendar folder – a
message said attachments can't be added to the calendar.  

If they do a File, Save As it saves it as a text file.  

How does the recipient get the appointment into their calendar?