does the current Combine Harvester use "incremental 
harvesting"?ie  sweeps only bring in new and modified 
documents"

In a document I was reading on the web.
<http://www.lib.helsinki.fi/tietolinja/0100/nwa.pdf>

"Combine requires the user to harvest
everything every time, while Nedlib harvester also supports 
incremental harvesting"

I have no idea of the date of this document and
features change so much with versions. But I coudd
 not find any documentation abput Combine Harvester 
relating to "incremental harvesting".

Thanks in advance

Brian Sweeney