ary ▁Places " ▁which ▁can ▁be ▁offered ▁to ▁pros pective ▁students ▁at ▁the ▁dis cret ion ▁of ▁each ▁school , ▁while ▁the ▁other ▁half ▁are ▁reserved ▁for ▁central ▁allocation . ▁All ▁parents ▁who ▁intend ▁to ▁send ▁their ▁child ▁to ▁a ▁public ▁primary ▁school ▁in ▁Hong ▁Kong ▁are ▁required ▁to ▁particip ate ▁in ▁the ▁PO A ▁System . ▁Par ents ▁must ▁obtain ▁an ▁application ▁form ▁and ▁indicate ▁whether ▁they ▁have ▁a ▁preference ▁for ▁any ▁particular ▁school . ▁Par ents ▁may ▁opt ▁to ▁apply ▁for ▁a ▁Dis cret ion ary ▁Place ▁at ▁one ▁single ▁school ▁of ▁their ▁choice ▁directly ; ▁the ▁school ▁does ▁not ▁have ▁to ▁be ▁located ▁in ▁the ▁same ▁school ▁net ▁as ▁the ▁child ' s ▁resident ial ▁address . ▁Par ents ▁who ▁have ▁no ▁preference , ▁or ▁who ▁failed ▁to ▁obtain ▁a ▁Dis cret ion ary ▁Place , ▁are ▁allocated ▁a ▁school ▁place ▁during ▁the ▁Central ▁Al location ▁stage . ▁ ▁Dis cret ion ary ▁Places ▁Dis cret ion ary ▁Places ▁are ▁split ▁into ▁two ▁categories . ▁Of ▁the ▁Dis cret ion ary ▁Places ▁( which ▁compr ise ▁ 5 0 % ▁of ▁all ▁places ▁offered ), ▁up ▁to ▁ 3 0 % ▁( out ▁of ▁ 5 0 %) ▁are ▁reserved ▁for ▁applic ant ▁children ▁whose ▁sib lings ▁study ▁at ▁a ▁particular ▁school ▁or ▁whose ▁parents ▁work ▁there ▁at ▁the ▁time ▁of ▁application , ▁with ▁the ▁remaining ▁ 2 0 % ▁or ▁more ▁reserved ▁for ▁points - based ▁ad mission . ▁School s ▁are ▁required ▁to ▁admit ▁students ▁in ▁the ▁first