Outlook compatible recurring events

[Jerry Pommer]

 Hello,   

I am working on Kolab object compatibility for a webmail offering. The goal of this product is to be as interoperable with Outlook as possible. We have an Outlook add-on that also uses the Kolab format. 

I am working with recurring events, and need to find a way to represent cases such as:

1) the last day of every month
2) the last weekday of every month
3) the last Thursday of every month
4) the last weekend day of every month

I have not been able to find a combination that works to represent the "last X of the month" case. Is there a way? And if there currently is not, what would be an acceptable implementation?

Thank you,
Jerry