How to automatically assign a (sequential) number to a user-created node I'm designing a website for a group of academics.  I've created a content type, called "Preprints," where users enter information about a paper they have recently submitted to an outside journal for publication. When created, these nodes are then listed on a Views page, also called "Preprints." The users, however, would like some way of tracking the order in which they submit their Preprint. Thus, I'd like to figure out some way of automatically assigning each node a number or a code. (For example, the first paper of the year would be assigned the code LPS13001, the second would be LPS13002, and so on.)  My first thought was to do this through a custom field, but I haven't been able to figure this out. Any help would be greatly appreciated!
The Serial module allows you to do exactly that. You can simply have an integer number that is incremented per content type and if you wanted a prefix you could do that in the display formatter.


  Unlike Drupal's built-in auto-increment node ID, which is global and
  shared by nodes belonging to all content types, serial fields are
  managed per content type (D6) / entity (D7). For example, the serial
  field of an Invoice instance will generate a unique sequential number
  (starting at 1, then 2, etc.) exclusively for Invoice instances.