One problem that seems to cal1 for some consideration is the fa& that costs for the use of buildings are reported under severa1 items. Item 1.2.1 "Materials for current use" includes for instance the costs for heating (petroleum products) in case the military sector pays for these costs separately. In other cases, when they are paid for as an integral part of the rent costs, they will normally appear under 1.2.4 "Real estate rents". It is the same thing with, the costs of maintenance, which may be reported separately under 1.2.3 "Maintenance and repair" but also fa11 under item 1.2.4. Considering this rather confusing pattern i-t may be preferable to instruct the respondents to report al1 kinds of rent costs under one single item. / . , . -569 Foot-note (k): Concerning such major weapons systems that were procured by Swedish forces in the reporting year their average-length-of-service rates could be roughly estimated as follows. 2.1.1 Aircraft (system 37 Viggen) .,................... 15 years 2.1.2 Missiles etc. (mainly air defence and air-to-air missiles) I.....................,...........,.... 15 H 2.1.4 Ships and boats (patrol-boats) ..,., ..* . . . . . . . . . . 25 " 2.1.5 Armoured vehicles (light tanks) . . . . . ..*......... 25 '9 During the same year equivalent equipment of the same order and magnítude has been taken out of service so in no case has the procurement of new systems led to an increase of military equipment within the artned forces. Foot-note (t): Cne problem has been to distribute such research costs which could not be referred to any particular forte group. As a consequence of this, the figures reported in the different columns under items 3 and 3.1 do not ada up to the total figure given in column 13. A way of eliminating 
**Analysis**
The text appears to be discussing financial and accounting issues related to military expenses and equipment, making it likely that it falls under a category related to finance, industry, or defense. The mention of specific military equipment and weapons systems also suggests a strong connection to the defense sector.

**Category**
Industry, Defense