was posted before "last visit time" is considered "read" regardless of whether the user has actually seen it or not. Until the user's session expires, this method properly tracks read/unread messages, starting with messages that were selected as "unread" when the user's session started. This method is broadly used, due to the simplicity and speed benefits of only storing and checking against a single database value. Full — forum software which records in the persistent database what messages have been read or unread by each user, regardless of user session expiration. Some forum software also allows the user to 'mark as unread', so that they can come back to a message later. Export, portability This column judges the ability to allow users to export data from the forum installation and then import it in new installations of the same software (cf. right to fork and data portability) or feed it to data conversion tools. Software portability is a key assessment criterion for the choice and procurement of software. Email/NNTP interface Whether the software can be used with standard Email or NNTP clients. Adoption of standard protocols is key for interoperability. Languages Whether the internationalization and localization of the software are sufficient to both allow and actually provide grammatically correct support for the native language of the target users. For the purposes of this table, we consider languages used by a number of installations/users equal to at least 1% of the top million web properties using that software, without major reported bugs in support. Single sign-on Single sign-on is often required to enhance web accessibility of the application. This can be accomplished with standards like OAuth and OpenID. Post drafts To prevent loss of content from browser crashes and the like, forum software may be equipped with the ability to automatically save unfinished posts as drafts, like some word processor and text editor software. Drafts may be stored server-side (in the forum account) or client-side (browser's local storage). The former benefits from the ability to immediately resume drafts on another device, whereas the latter allows saving drafts while internet is disconnected and slightly reduces bandwidth consumption. Other features Duplicate thread prevention Automatic recommendation systems based on content and users can help forum users find existing discussions similar to those they are browsing or on the topic they are searching, or else reach the correct users with their posts, avoiding to "spam"