No appeal, application or petition which has been unfavorably
and finally acted upon by the special permit granting authority or
the Board of Appeals shall be acted favorably upon within two years
after the date of final unfavorable action unless said special permit
granting authority or Board of Appeals finds, by a unanimous vote
of a board of three members or by a vote of four members of a board
of five members or two-thirds vote of a board of more than five members,
specific and material changes in the conditions upon which the previous
unfavorable action was based, and describes such changes in the record
of its proceedings, and unless all but one of the members of the Planning
Board consents thereto and after notice is given to parties in interest
of the time and place of the proceedings when the question of such
consent will be considered. Any petition for a variance or application
for a special permit which has been transmitted to the special permit
granting authority or Board of Appeals may be withdrawn, without prejudice
by the petitioner prior to the publication of the notice of a public
hearing thereon, but thereafter be withdrawn without prejudice only
with the approval of the special permit granting authority or the
Board of Appeals.