In addition to the text-book examples I posted earlier, here are several variations on how documents were sealed in period.
Charter of Henry I, c1109, sealed on a tongue that appears to be folded double.
Confirmation of cathedral chapter of episcopal grant, 1149. Tag cuts through the body of the document as well as the turn up.
Writ of Henry II, 1173, with two tongues cut haphazardly into the document.
Forged charter of Bishop William of St Calais, c1160, showing long seal tag and close tape.
Grant recording perambulation, 1165. This definitely shows the tag fed through a slot in the fold of the turn up.
Grant of marriage portion, 12th century. Obviously not that great a portion.
Draft charter c1180, showing adding clauses by attaching an extra slip of vellum. This approach could also potentially be used for signatures.
Another example of the tag threaded through a cut on the fold.
Mandate of Pope Innocent III, 1211. The seal cord has presumably deteriorated to reveal the threading hole for a V pattern.
Appropriation of Aycliffe church by Bishop Marsh, c1220. An unusual example of two mismatched cords threaded in a triangle pattern. One looks to be braided cord, the other appears to be tablet woven in a check pattern. Can any textile people have a guess?
I have no idea what's going on with this one.
Chirograph document, and example of a tag cut from previously used vellum which it seems was not uncommon.
Coal mining and transport concession, c1258, with signatures on the fold as well as tags.
Mandate of Popr Martin IV for legal case, 1284. An example of what looks to be a single hemp cord knotted around itself.
Allowance of expenses for exemption of taxation, 1296. An example of letters close here shown open...
...and closed. The second long thin strip threaded at right angles to the tongue wraps the folded document and holds it closed, with the seal tucked inside. The date and presumably the bearer are written on the dorse of the closed packet.
Another example from 1304, a bond receipt for the loan of a book shown open and closed.
And another, receipt of proctor in the papal curia, 1312. This example shows how the long strip was wrapped and tied to keep the document closed.
Receipt f0r 200 marks, 1326. The tongue supports the seal, while the upturned fold is cut into a long strip, becoming the tape for letters close.
Knotted seal cords again, in an illuminated charter c1386. Two cords knotted once at the base of the document, then passing here through a wooden case to protect the fragile wax seal.
And again with bi-coloured cords in a diamond pattern, from inspeximus confirmation of Henry IV, 1401.
Oath of fidelity of William Raket, 1402, which presumably, is a letter containing his promise of fidelity backed up by a lot of character witnesses for said gentleman.
Mandate of a bishop for attendance at Parliament, 1402. Similar to a seal bag, this document shows the seal protected by being slipped into a seal packet, a sort of envelope made from previously used vellum.
Receipts for silver plate and salts, 1438. Multiple seals on tongue.
Legal verdict on the descendants of John Middleton, 1475. The more the merrier.
All documents collection of Durham University.
Goes to show there is more than one way to skin a cat!