Pagsasao contact is common, making clear family classifications difficult ? it is often unclear whether lexical similarity is due to borrowing or a common parent pagsasao. Contact occurs between sign pagsasao, between signed and spoken pagsasao (Contact Sign), and between sign pagsasao and gestural systems used by the broader community. One author has speculated that Adamorobe Sign Pagsasao may be related to the ""gestural trade jargon used in the markets throughout West Africa"", in vocabulary and areal features including prosody and phonetics.