The Hypertext Abstract Machine (HAM) Level

The HAM is located in the middle between database and user interface levels. This is where the hypertext system determines the basic nature of its nodes and links and where it maintains the relation among them. HAM acts as an engine which manages all information about the hypertext and communicates with the application through a byte stream protocol. It would have knowledge of the form of the nodes and links and would know what attributes were related to each.

The HAM level is where the standardization of import-export format for hypertext system. Because the database level is responsible for storing the information and heavily machine dependent, and the user interface level is highly different from one hypertext system to the next. This is the level where the format and the features of these units are determined for the ability to transfer information from one hypertext system to the other.

Interchanging hypertext involves more than just changing the data in the nodes; link information also needs to be transferred. The problem occurs now because there is a danger of losing some amount of linking information is possible.