Igiceri cy'icyuma, kizwi kandi nk'icyuma gikonje.Ibyuma birashyushye kandi bikonje bikonje.Mu rwego rwo koroshya ububiko no gutwara, no koroshya gutunganya ibintu bitandukanye (urugero, gutunganya ibyuma, ibyuma umukandara, nibindi) Ibiceri bishushanyije, cyangwa ibyuma bishushanyijeho, byitwa kandi ibyuma bisubira inyuma, aribyo byuma bifite rombus cyangwa imbavu. hejuru.Bitewe n'imbavu ziri hejuru yacyo, isahani yicyuma ifite ingaruka zo kurwanya skid, kandi irashobora gukoreshwa nka etage, escalator yinganda, ikariso yakazi, inzu yubwato, hasi yimodoka, nibindi. Ibisobanuro byibyuma byagenzuwe bigaragazwa mumagambo y'ububyimbye bwibanze (utabariyemo umubyimba wimbavu), kandi haribisobanuro 10 bya mm 2,5-8.No 1-3 ikoreshwa mubyuma byagenzuwe.