CO-OPERATIVE WHOLESALE ESTABLISHMENT, CEYLON FERTILISER CO.LTD&OTHER MAJOR IMPORTERS OF FERTILISER,CEYLON PETRO COR History is stored independently for monthly and yearly frequencies. HP values for these frequencies may not match each other. Note that when only one frequency is stored in history, for the other frequencies, history is derived from that of the stored frequency. For example, HP W, HP M, HP Q and HP Y will derive data from HP D when only daily history is stored, HP Q and HP Y will derive data from HP M when only monthly history is stored. As another example, if both daily and monthly are stored, HP W will derive data from HP D, while HP Q and HP Y will derive data from HP M and so on.