It seems well-known that the SWR value that you read on an external meter
or
an antenna tuner is NOT the value measured between itself and the antenna.
The SWR value "picked-up" and that you can change is the one measured
between this meter or tuner and the transceiver (or the linear amplifier
but
we consider it as a black box if you use it properly).

But recently I experimented the burning of my PL due to a high SWR, thus
high current, and moisture and the end of the line (really, see image of
PL's here http://www.astrosurf.com/lombry/qsl-...sion-line2.htm, end
of
page ).

The distance between my RTX and SWR reader is short, about 1 m. But there
are about 15m between the SWR and the feed point of my antenna where I had
the problem.

So I would like to know if an SWR meter does only read the value upstream
or
if the properties of the feedline to the antenna does not influence is
reading.

The SWR meter indicates the value from the meter to whatever is after it.
If you insert a device that has a high SWR (because it becomes defective or
for some other reason ) between the transmitter and SWR meter ( say a switch
or filter), the meter can show a low value if the antenna is ok, but the
transmitter will see a high SWR and may burn out the finals.