Back-bond

The following was originally from the 1911 Encyclopedia Britannica. As such, it may not yet be properly adapted to Wikipedia (obsolete, typos, no accidental links, etc.). It is included as a stub of sorts to inspire people to modify it:

BACK-BOND, or BACK-LETTER, in Scots law, a deed qualifying the terms of another deed, or declaratory of the purposes for which another deed has been granted. Thus an ex facie absolute disposition, qualified by a back-bond expressing the limited nature of the right actually, held by the person to whom the disposition is made, would constitute what in England is termed a deed of trust.