hereto comes from here (Old English hēr) + to (Old English tō); a formal and legal adverb meaning 'to this document or matter'. The history explains the modern form through the named earlier word or formation, without requiring a separate speculative ancestry. In present English, the adverb sense is "to this document or matter (formal and legal)", so the historical development ends in a clearly identifiable modern dictionary use. The same base also appears in related forms such as here, hereunto, thereto, and whereto. Its semantic neighborhood includes herein, hereunto, and attached, which helps locate the modern sense without adding a separate etymological claim. The named historical forms include Old English hēr and Old English tō.