import re


def split_field(line):
  """ Split a string on the first ':' character """
  ## beware of lines that hold dates!!
  ## e.g. Date Installed           : 1995-05-13T00:00Z
  l = line.split(':')
  if len(l) > 1:
    ## handle cases where the default (driver) string is there, e.g.
    ## (A*, but note the first A5 is used in SINEX), or
    ## (A20, from rcvr_ant.tab; see instructions)
    ## replace with empty string
    value = '' if re.match(r"^\(A[0-9\*]+.*\)$", ':'.join(l[1:]).strip()) else ':'.join(l[1:]).strip()
    #return l[0].strip(), ':'.join(l[1:]).strip()
    return l[0].strip(), value
  else:
    return line.strip(), None