▁st all ions ▁imported ▁to ▁England ▁from ▁the ▁Middle ▁East ▁that ▁became ▁the ▁foundation ▁st all ions ▁for ▁the ▁bre ed . ▁ ▁Some ▁bre ed ▁reg ist ries ▁have ▁a ▁closed ▁stud ▁book , ▁where ▁registration ▁is ▁based ▁on ▁pedig ree , ▁and ▁no ▁outside ▁animals ▁can ▁gain ▁adm itt ance . ▁ ▁For ▁example , ▁a ▁registered ▁Thor ough bre d ▁or ▁Arab ian ▁must ▁have ▁two ▁registered ▁parents ▁of ▁the ▁same ▁bre ed . ▁▁ ▁Other ▁bre eds ▁have ▁a ▁partially ▁closed ▁stud ▁book , ▁but ▁still ▁allow ▁certain ▁inf us ions ▁from ▁other ▁bre eds . ▁ ▁For ▁example , ▁the ▁modern ▁App alo osa ▁must ▁have ▁at ▁least ▁one ▁App alo osa ▁parent , ▁but ▁may ▁also ▁have ▁a ▁Qu arter ▁Hor se , ▁Thor ough bre d , ▁or ▁Arab ian ▁parent , ▁so ▁long ▁as ▁the ▁off spring ▁exhib its ▁appropriate ▁color ▁characteristics . ▁The ▁Qu arter ▁Hor se ▁normally ▁requires ▁both ▁parents ▁to ▁be ▁registered ▁Qu arter ▁H ors es , ▁but ▁allows ▁" Append ix " ▁registration ▁of ▁horses ▁with ▁one ▁Thor ough bre d ▁parent , ▁and ▁the ▁horse ▁may ▁ear n ▁its ▁way ▁to ▁full ▁registration ▁by ▁comple ting ▁certain ▁performance ▁requirements . ▁ ▁Open ▁stud ▁books ▁exist ▁for ▁horse ▁bre eds ▁that ▁either ▁have ▁not ▁yet ▁developed ▁a ▁rig or ously ▁defined ▁standard ▁phen ot ype , ▁or ▁for ▁bre eds ▁that ▁register ▁animals ▁that ▁conform ▁to ▁an ▁ideal ▁via ▁the ▁process ▁of ▁passing ▁a ▁stud book ▁selection ▁process . ▁