arcgis desktop - Referencing other points(rows) in field calculator

I'm trying to calculate an angle between points using a field calculator. Is it possible to reference the previous or next FID with reference to the current one using the field calc?

Eventually I'd like to have an angle between the next and previous point be input into a field for the current point - like shown below

Answer

Yes, you can access previous values with Field Calculator. I'd suggest migrating to Python and using update cursors, where it would be a lot simpler to work with values forward (via reading into a list) or reverse.

Code Block:

prev=None
def diff(curr): 
  global prev
  if prev is None:
    prev = curr
  res = curr - prev
  prev = curr

  return res

Expression: diff(!test!)