Let us assume that ** f is identical to the form of an occurrence ** f which preceded ** f in the text. When this situation exists, the address ** f will equal ** f which was produced from ** f. If ** f was assigned as the information cell for ** f, the routine can detect that ** f is identical to ** f by comparing ** f with the form stored at location ** f. The address ** f is stored in the cell ** f. When, as in this case, the two forms match, the address ** f is saved to represent the occurrence ** f. Text reading continues with the next occurrence.

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 ** f leads to an address ** f that is equal to the address computed from ** f, even though ** f does not match ** f, the chain of information cells is extended from ** f by storing the address of the next available cell in the Y-region, ** f, in ** f. The cell ** f becomes the second information cell in the chain and is assigned as the information cell of ** f. A third cell can be added by storing the address of another Y-cell in ** f; 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 ** f is computed from ** f, the cell ** f and all Y-cells in its chain must be inspected to determine whether ** f is already in the form list or whether it should be added to the form list and the chain. When the information cell for ** f has been determined, it is saved as a representation of ** f. Text reading continues with the next occurrence.