[Elecraft] Accuracy of W1 wattmeter

[Vic K2VCO]

The new W1 wattmeter is spec'd to provide 0.5 db accuracy.  Is this 0.5 
db of full scale or of the actual reading?

If the former, then I figure that the reading at 5 watts would be plus 
or minus about 1.8 watts.  If the latter, about 0.6 watts (I am not good 
at doing this stuff in my head -- is this right)?
-- 
73,
Vic, K2VCO
Fresno CA
http://www.qsl.net/k2vco