php ini y2k_compliance

Some users may be using wildly outdated, noncompliant browsers. If for some bizarre reason you're sure that a number of your site's users fall into this group, then disable the y2k_compliance parameter; otherwise, it should be enabled.

y2k_compliance = On

Specifies whether or not the PHP script should be made year-2000 compliant. Making the PHP script Y2K compliant (by setting this directive to On) will cause problems with non-Y2K-compliant browsers.