* in a contiguous array once and only once when the table is created.
* this is done for forwarding performance. The entry is thus not subject
* to realloc, and does not need to be malloc'd when a route to that
* in a contiguous array once and only once when the table is created.
* this is done for forwarding performance. The entry is thus not subject
* to realloc, and does not need to be malloc'd when a route to that