6. In March 1976 the Department of Energy issued an explanatory supplement to its bulletin, Energy Trends! Read the following extract and answer the questions which follow it:

Gas (Tables 7-8)
Table 7: Natural gas supply is the total natural gas input (including imported natural gas) into the public supply system after stock changes at gas supply installations have been taken into account. Indigenous supplies consist almost entirely of purchases by the gas supply industry from operators on the UK part of the Continental Shelf. 'Gas sent out'
covers town gas (that is, gas made from coal or oil) and natural gas for direct supply (including gas supplied for non-energy purposes).
Table 8: Gas sales are the quantities estimated to be sold and consumed during each period, and differ from 'Gas sent out' mainly because of losses in transmission and consumption in the offices and showrooms of the gas supply industry.

(a) From what you read you should be able to make a confident guess as to the subject of Table 7 and Table 8 and hence their titles.
Suggest a title for each table.

(b) In a given period, which would normally record the higher figures and why -Table 7 or Table 8?

(c) Explain in your own words what you understand by any two of the following: indigenous supplies; Continental Shelf; transmission.

(d) If there is an increase in the supply of home-produced natural gas but no increase in the amount of natural gas supplied to the public, state in your own words the two possible reasons for this.
(LCC Private Secretary's Certificate)