In North America, languages of the Siouan and Chemakuan families have similarly structured basic systems (Siouan prefixal, Chemakuan suffixal), but mostly with spatial reference. i- is standing out, away from some surface, a- is surface contact, and u- is containment within a surface, though there are also processual and figure/ground senses involved. Note that standing away minimizes surface contact. Other language families have distance demonstratives which follow similar phonological clines. It is possible that there may be historical connections between the y- form and ki:pa 'woman' and u:- and u:a 'man', which when verbalized apparently refer to less and more forceful or determined attempts to achieve respectively. Verbs ya:na 'to intend, wish' and wa:na 'pass, surpass', as well as u:a- 'do fiercely, forcibly' may be related, with suffixal -na on the first forms.