User signatures no longer inherit comment input formats. Each user's signature now has its own associated format that can be selected on the user's account page. Existing signatures have been set to your site's default input format.
Drupal好像对用户签名作了完善,,每个用户的签名,现在都有了自己独立的格式.而已有的签名,则被设置为站点的默认输入格式.
