Thanks for the comprehensive explanation Martin.
So just to clarify if I understand correctly;
If we want to plot our maps with respect to magnetic north (to be compatible
with 'old' uncorrected surveys for example) then we do not specify
declination and we do not specify any co-ordinate
On Mon, Jul 28, 2008 at 12:20 PM, Bruce Mutton
wrote:
> So just to clarify if I understand correctly;
>
> If we want to plot our maps with respect to magnetic north (to be compatible
> with 'old' uncorrected surveys for example) then we do not specify
> declination and we do not specify any
Martin Budaj wrote:
>
>> The grid north is usually not the same as the true (astronomical) north, but
>> for the purposes of cave maps and Therion I would assume it is usually
>> considered to be so. (Not strictly correct, but I imagine the error would
>> not be detectable on any printed cave map
