In database (2.2.3.1 version of cmsms) extra page attributes are defined as varchar(255) in table cms_content_props , same thing for titleattribute in table cms_content.
Is there a technical reason for such a low limitation ?
For SEO purpose this fields are very useful and it would be really interesting to have a larger limit (500 carachters would be great)

Consequently, input fields should be transformed into fields of type textearea in the administration interface.