Pre-infringement
Contracts
Contracts are a pre-infringement control method, which very often is underestimated. Properly formed contracts enable copyright holders to restrict the use of their works in excess of the rights granted under copyright laws.
Copy Protection
This approach was standard in the 1980s, but rejected by consumers and relatively easy to break. Still copy protection, whereby the vendor limits the number of times a file can be copied, is used in certain situations.
Limited Functionality
This method allows copyright owners to provide a copy of the work, which is functionally limited. Software creators, for example, can distribute software that cannot print or save. A fully functional version has to be bought from the vendor.
Date Bombs
Here the intellectual property holder distributes a fully functional copy but locks off access at a pre-specified date or after a certain number of uses.
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Aeneas Tacitus, a Greek military scientist and cryptographer, invented an optical communication system that combines water and beacon telegraphy. Torches indicated the beginnings and the ends of message transmissions while water jars were used to transmit the messages. These jars had a plugged standard-size hole drilled on the bottom side and were filled with water. As those who sent and those who received the message unplugged the jars simultaneously, the water drained out. Because the transmitted messages corresponded to water levels, the sender indicated by torch signal that the appropriate water level has been reached. It is a disadvantage that the possible messages are restricted to a given code, but as this system was mainly used for military purposes, this was offset by the advantage that it was almost impossible for outsiders to understand these messages unless they possessed the codebook.
With communication separated from transportation, the distant became near.
Tacitus' telegraph system was very fast and not excelled until
For further information see Joanne Chang & Anna Soellner, Decoding Device,
The Roman smoke signals network consisted of towers within visible range of each other and had a total length of about 4500 kilometers. It was used for military signaling.
For a similar telegraph network in ancient Greece see