Base year is 2010=100. The Index of Production incorporates annually weighted and chained estimates of volume measures with base year T-3. For further Economic Statistics for the UK, please tpye ECST GB<GO> History is stored independently for monthly and quarterly 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.