That khipu record numbers in a decimal positional system is settled and readable. Beyond that the field divides. Gary Urton argues that the binary structural choices available in the medium, in colour, spin, ply and attachment, give it an information capacity well beyond accounting. Others hold the cords numerical, with any narrative held in the specialist's memory and the khipu serving as a mnemonic prompt. Colonial testimony describing khipu specialists reading out histories and confessional records is compatible with both, because a skilled performance from a numerical prompt looks identical to a reading.
What would resolve this A matched pair: one khipu and an independent Spanish document recording the same content, aligned closely enough that the correspondence cannot be coincidence. A small number of candidate matches have been proposed and none is yet accepted as conclusive. Progress requires archival paleography alongside statistical analysis of the surviving corpus of roughly a thousand khipu.
OpenAndean archaeology, colonial paleography and quantitative analysis of the khipu corpusGary Urton, Signs of the Inka Khipu: Binary Coding in the Andean Knotted-String Records