sync headers to download with server

when I select a group to enter, I get
prompted for how many headers,

is this the number of headers on the server?

how can I get only new headers from the time
I used it last?

I am a previous Thunderbird/pan user who switched
to slrn mainly for memory footprint issues,
I only have 993MB RAM and am using Ubuntu

Thunderbird/pan seemed to "sync" the headers,
is there a way to do this with slrn?

-- 
(my whereabouts below)
http://www.dalekelly.org

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