Page "learned" Paragraph 543

A third situation is possible.

The formula for computing random addresses from the form of each occurrence will not give a distinct address for each distinct form.

Thus, when more than one distinct form leads to a particular cell in the X-region, a chain of information cells must be created to accommodate the forms, one cell in the chain for each form.

If Af leads to an address Af that is equal to the address computed from Af, even though Af does not match Af, the chain of information cells is extended from Af by storing the address of the next available cell in the Y-region, Af, in Af.

The cell Af becomes the second information cell in the chain and is assigned as the information cell of Af.

A third cell can be added by storing the address of another Y-cell in Af ; ;

similarly, as many cells are added as are required.

Each information cell in the chain contains the address of the Y-cell where the form to which it is assigned is stored.

Each cell except the last in the chain also contains the address of the Y-cell that is the next element of the chain ; ;

the absence of such a link in the last cell indicates the end of the chain.

Hence, when the address Af is computed from Af, the cell Af and all Y-cells in its chain must be inspected to determine whether Af is already in the form list or whether it should be added to the form list and the chain.

When the information cell for Af has been determined, it is saved as a representation of Af.

Text reading continues with the next occurrence.