[Elecraft] Spectrogram and frequency markers

[belsley]

I note a number of people suggesting the use of Spectrogram's frequency 
markers as means of determining, say, 500 or 600 Hz.  Just how precise 
are these markers in Spectrogram?  Do they not depend on some 
frequency standard in the computer, and as such, are they not themselves 
subject to error and change somewhat from computer to computer?  What 
sort of precision is to be expected?

thanks,

dave belsley, w1euy