text: heterogeneous than those that fall within the category of operating costs, This is probably even more so when only a limited period of time is taken into account, as in this exercise, inasmuch as several expensive types of equipment are procured by most countries only infreauently. 76. The Group, therefore, did not specify any particular items in its questionnaire for this cost category. The Group did, however, specify types of items within most of the sub-subcategories and request the contacts to find such items that might have been delivered in the 1980-1982 period and to submit prices and product descriptions for each of them. 77. Table 2 shows the types of items which the Group decided to work with, and table 3 gives two examples of the kind of data which was requested for separate items. 78. To this questionnaire, the Group attached a set of instructions or guidelines which should help the respondents to adopt a similar approach with regard to the determination of unit prices and other related matters. These instructions are reproduced in appendix III. 79. In response to this questionnaire, the Group received information on several items from all participants. The data that were submitted to the Group at some stage of its exercise are indicated in table 4 showing the number of items for which prices were reported. It should be noted that empty cells in this table does not necessarily indicate unwillingness to provide data, but may merely reflect the absence of the procurement of Particular types of items in the prescribed time period. / . . . A/40/421 English Page 25 1 1 Table 2. Main structure of the Group's auestionnaire on procurement and construction 2.1.1 Aircraft and enqines Transport aircraft Fighter aircraft Attack aircraft Bomber aircraft Bomber aircraft Reconnaissance aircraft Transport helicopters Attack helicopters Engines 
analysis: The text appears to be discussing a specific exercise or study related to procurement and construction of equipment, likely in the context of international development or economic cooperation. The categories of equipment mentioned, such as aircraft and engines, suggest a focus on industrial or technological development, which is often related to economic development and international trade.