For example, the lines of magnetic variation will be shown on the chart, but under the legend it will be stated how many minutes per year these lines will incline eastwards or westwards and the amount of this annual variation line change must be multiplied by the number of years that have elapsed since the date the chart was printed.
Umzekelo, imigca kamazibuthe eyahlukileyo izakeuboniswa kwitshati, kodwa phantsi kweleva izakuba ichaza ukuba mingaphi imizuzu ngonyaka le migca izakunyukela kwiwardi yasesMpuma okanye eNtshona kunye nemali yonyaka yokwahuka kotshintsho lomgca ekufuneka iphinda-phindwe ngenani lonyaka iphelile ukusukela ngomhla eyayibhalwe ngawo itshati.