Sigil Sequence

A sigil sequence, sometimes called a Portal Address, is a unique series of symbols that corresponds to a specific permanent teleportation circle or a Portal Monolith.
The enchantments involved in the creation of a portal monolith or circle, involve use of divination magic that enables the creator to produce a series of symbols that are unique to that specific portal and not in use anywhere else in the multiverse.
On Erdos, knowledge of sequences of Portal Monoliths is regulated, so as to control access. That said, the primary means of said regulation is nothing more than having each sequence behind a paywall. Generally, the ones most interested in the buying of sigil sequences are adventurers.