Abiding by a European privacy panel's request for a common standard for the anonymization of search data, Microsoft on Monday proposed that a six-month search data retention period should be set as an industry standard. At present, Microsoft's MSN Live Search retains search data for 18 months; while Yahoo keeps data for
13 months, and Google for 9 months.

The Article 29 Working Party issued an opinion in April that there was no basis to keep search data more than six months. It also said that only the cookie files deposited on the computers of the users, for tracking and identification, should be kept for an unlimited period.

Microsoft appears to be more willing to accede to the Article 29 Working Party's recommendations of the full anonymization of IP addresses after six month and the deletion of cookies and cross-session identifiers. At this point, Microsoft's support of the recommendations probably stems from the fact that it has far less to lose in search advertising revenue under a more stringent data retention regime.

However, John Vassallo, a lawyer for Microsoft, said the company was not willing to act alone because doing so would create a commercial disadvantage.

Vassallo, who is based in Brussels, said: "We support the commissioners' recommendations, but are asking them to ensure these are uniformly observed. Otherwise, to do so unilaterally would put us at a disadvantage."

Meanwhile, Google, in reducing its search data retention period to nine months in September, had noted that "it was a difficult decision because the routine server log data we collect has always been a critical ingredient of innovation." The company has said that it uses search data to improve search quality, to improve security, to fight fraud, and to reduce spam.