Session 613 is the In Character pesterchum memo for Session 613 of Sgrub/Sburb. It is ICly a persistent text-based chat forum, and all characters should have a two-word IC handle and a handle color. For example, Vruasa Telash's is: deusexLongcoat (DL, and Arthur Lowell's is: profoundBadness (PB). Colors and letter combinations should be unique where possible.
As of 12-27-2013, this memo is ICly available. Those who were involved previously may assume that they have been contacted by relevant individuals and given access. The IC explanation is simple: Session 613 of Sgrub concluded at the end of August alongside Session 412, but a number of unknown individuals (and a few known individuals, including the Players of Session 412) were involved in assisting the completion of Session 613 by means of a series of time loops.
If you were involved in Session 412, you may assume somebody relevant (probably Arthur or Vruasa or Fiora) invited you. If NOT, you'll need to wait until the TP begins properly for a hook. (Don't worry, I'll make it easy for you.) The purpose of the Session 613 +group is to coordinate all individuals involved in the relevant time loops (some of whom are ICly unknown), and make certain they are where they were supposed to be at the relevant time.