ubimarks protocol

I've just been looking at ubimarks and can't wait (to find the time) to 
write an adaptor so bookmarks can be store on and retrieved from KnoBot  
[1]. I may have missed some documents however as I couldn't find 
description on the cleint-server protocol. Ubimarks makes an http-put 
request to store the bookmarks, does this mean that all bookmarks should 
be stored on every change, or has a way already be specified to only 
transmit a new bookmark to a server or a modification to the server?

reto

1. http://wymiwyg.org/knobot