Section 706. Grounds for review; contents of petition

1. The grounds for
  reviewing an assessment shall be that the assessment to be  reviewed  is
  excessive, unequal or unlawful, or that real property is misclassified.
    2.  A  proceeding  to  review  an  assessment  shall be founded upon a
  petition setting forth the respect in which the assessment is excessive,
  unequal  or  unlawful,  or  the  respect  in  which  real  property   is
  misclassified  and  stating  that  the  petitioner is or will be injured
  thereby. Such petition shall be duly  verified  by  the  petitioner,  an
  officer  thereof,  or  by  an  agent  thereof who has been authorized in
  writing to verify and file such petition and whose authorization is made
  a part of such petition. Such petition must show that  a  complaint  was
  made  in due time to the proper officers to correct such assessment. Two
  or more persons having real property assessed upon  the  same  roll  who
  assert  the  same grounds for review presenting a common question of law
  or fact, may unite in the same petition.