On its limited surface of 6,5 cm in diameter the token indicates a spot on our planet with an precision of some ten meters: The entry to the MOM archive.
The front-side depicts the outline of Europe, crosshairs and some scrawls. The crosshairs represent north-south resp. east-west (or longitude and latitude) with the crossing point Hallstatt.
The scrawls show enlargements of the coastlines of Norway resp. France together with the same longitude/latitude of Hallstatt. With an accuracy of some kilometers the MOM archive is indicated that way.
The backside shows the shape of the Hallstatt Lake and the position of the entry to the MOM archive relatively to the lake. In addition there is a hint to the salt mineral (a cubic structure).
The token can only be deciphered by someone with an exact coordinate system and an understanding of geological processes - hence a level of knowledge as we had since the mid 1980s - capable of reconstructing a coastline after a change of sea level or the altered shape of the Hallstatt Lake after an ice age.
As soon the entrance tunnel will not be maintained any more (for any reason) it starts to close itself. In this 2 km long tunnel a "Ariadne´s Thread" is lain: every 2 meters a small ceramic tablet mathematically displays: "tablet 1 of 1000", "tablet 2 of 1000", etc.
Every 50 meters there is a gap of missing tablets, also mathematically indicated on these tablets. Similar to pitfalls or dead ends in pharaonic tombs this shall keep away intruders which could not understand the content of the MOM archive.
As it is known there were already mining acivities in prehistoric times at this spot. The design of the token and the Ariadne´s Thread act as a barrier to protect the archive from accidential discovery by "immature" societies.