  Weak isolated X-ray precursor events before the main Gamma Ray Burst, GRB,
and also rare Soft Gamma Repeaters, SGR, events are in disagreement with any
Fireball, or Magnetar, scenarios.
  These models are originated by an unique explosive event leading, by
internal-external shock waves, to softer secondary trains following a main
gamma signals. Indeed the earliest GRB980519,GRB981226 events as well as the
latest and most distant identified one as GRB000131 are showing rare but well
identified and distinct X Ray precursor, occurring tens of seconds or even a
minute before the main GRB eruption. These weak X precursors bursts correspond
to non-negligible energy powers, up to million Supernova ones.
  They are rare, about (3-6)% of all GRBs, but not unique.
  Similar huge explosive precursor are in total disagreement with a successive
main Fireball GRB outburst.
  Comparable brief X-ray precursor flashes are found also in rarest and most
detailed SGRs events as those observed on 27 and 29 August 1999 from SGR
1900+14.
  They are inconsistent with a Magnetar Fireball explosion.
  We interpret them as earlier marginal blazing of outlying X conical Jet tails
surrounding a narrower gamma precessing,spinning beamed Jet in blazing mode
toward the Earth; later re-crossing and better hitting of the target -the
satellite detectors- is source of the main GRB (and SGR) observed structured
event.
  The X Ray precursor existence is an additional remarkable evidence of the
Precessing relativistic Jet Nature of both GRBs and SGRs.
