​A caveat is a legal document lodged with the Singapore Land Authority by a purchaser to protect his/her interests after an option to purchase is exercised or a Sales & Purchase Agreement is signed. We use information from caveats with "options exercised" to compute our property price indices. The transaction database in REALIS may not reflect all the units sold directly by developers, as the lodgement of caveats is voluntary, and there is usually a time-lag of a few months from the point of purchase of a private residential unit direct from a developer to the lodgement of a caveat for that unit.