A new (empty) & kformula; document looks like a small blue square. This square stands for the central idea of & kformula;. It represents an empty list. The idea of & kformula; is to have different elements arranged in lists. An element in this respect might be a single char or a root symbol or something like that. The lists are put together so that they form a formula. That is there are lists for indexes, lower and upper bounds and so on. And of course there is the main list, which we've already seen.
Un nou document de & kformula; (buit) té l' aspecte d' un requadre blau. Aquest requadre és la idea central del & kformula;. Representa una llista buida. La idea del & kformula; és la de tenir diferents elements arranjats en llistes. Un element, en aquest aspecte, pot ser un simple caràcter o un símbol d' arrel o alguna cosa com aquestes. Les llistes es posen juntes de manera que formen una fórmula. Llavors hi ha llistes per als índex, límits superior i inferior, etc. I, naturalment, hi ha la llista principal, que ja hem vist.