The $16.6 billion PCS preliminary insured-loss estimate was based on claims information available at that time for personal and commercial lines of insurance, it was explained.

PCS resurveys catastrophe losses after issuing preliminary estimates if insured property losses exceed $250 million, or specific circumstances relating to a catastrophe require additional analysis.

Following the re-survey, PCS's revised insured property loss estimates are as follows:

? New York--$20.3 billion from 30,000 personal, 15,000 commercial, and 4,000 auto claims.

? Virginia--$6.5 million from 1,500 personal, 200 commercial and 300 auto claims.

A full counting of insured losses in the aftermath of the attack was delayed by rescue operations and lack of access to the areas of destruction by claims adjusters, ISO noted.

ISO said that much uncertainty still surrounds property claims activity, and the PCS estimate is subject to change in the coming months.

The PCS loss estimate represents only property damage and related coverages, such as business-interruption insurance. The estimate does not include liability insurance, workers' compensation, aviation property-casualty losses, and life and health insurance.

ISO's PCS unit defines a catastrophe as an event that causes $25 million or more in insured property losses and affects a significant number of property-casualty policyholders and insurers.

PCS said its estimates represent anticipated insured loss on an industry-wide basis arising from catastrophes, reflecting the total net insurance payment for personal and commercial property lines of insurance covering fixed property, personal property, vehicles, boats, related property items, and business-interruption losses. The estimates exclude loss-adjustment expenses.