YOU can't take symbolism too literally at ground zero.

The great pool-filled memorial voids that are meant to mark the absence of the twin towers will be 31 percent smaller than the towers' actual footprints.

Each pool will be a 176-foot square, centered within the original 211-foot-10-inch-square footprint. The tower outlines will not be shown graphically on the plaza, so there will be no indication at ground level precisely where the twin towers stood; only an intimation.

It has been an open secret for almost two years that the pools would not faithfully represent the tower outlines. Official descriptions do not emphasize this fact but are also careful not to equate the pools and footprints exactly. The World Trade Center Memorial Foundation's Web site, for example, speaks of "two voids that reside in the original footprints" -- not "two voids that define the original footprints."

Only now, however, is the degree of discrepancy growing clear. On Dec. 5, the foundation and the Lower Manhattan Development Corporation issued a request for proposals from construction managers. It indicated that the pools would be 180-foot squares, a measurement that includes a parapet where victims' names will be inscribed.