▁as ▁to ▁provide ▁protection ▁from ▁the ▁force ▁of ▁explos ions . ▁ ▁A ▁garden ▁door ▁is ▁any ▁door ▁that ▁opens ▁to ▁a ▁back yard ▁or ▁garden . ▁This ▁term ▁is ▁often ▁used ▁specifically ▁for ▁French ▁windows , ▁double ▁French ▁doors ▁( with ▁l ites ▁instead ▁of ▁pan els ), ▁in ▁place ▁of ▁a ▁sl iding ▁glass ▁door . ▁The ▁term ▁also ▁may ▁refer ▁to ▁what ▁is ▁known ▁as ▁pat io ▁doors . ▁ ▁A ▁j ib ▁door ▁is ▁a ▁conce aled ▁door , ▁whose ▁surface ▁reflect s ▁the ▁m old ings ▁and ▁finish es ▁of ▁the ▁wall . ▁These ▁were ▁used ▁in ▁historic ▁English ▁houses , ▁mainly ▁as ▁servants ' ▁doors . ▁ ▁A ▁pet ▁door ▁( also ▁known ▁as ▁a ▁cat ▁f lap ▁or ▁dog ▁door ) ▁is ▁an ▁opening ▁in ▁a ▁door ▁to ▁allow ▁p ets ▁to ▁enter ▁and ▁exit ▁without ▁the ▁main ▁door ' s ▁being ▁opened . ▁It ▁may ▁be ▁simply ▁covered ▁by ▁a ▁rub ber ▁f lap , ▁or ▁it ▁may ▁be ▁an ▁actual ▁door ▁h ing ed ▁on ▁the ▁top ▁that ▁the ▁pet ▁can ▁push ▁through . ▁Pet ▁doors ▁may ▁be ▁mounted ▁in ▁a ▁sl iding ▁glass ▁door ▁as ▁a ▁new ▁( per man ent ▁or ▁temporary ) ▁panel . ▁Pet ▁doors ▁may ▁be ▁un id irection al , ▁only ▁allowing ▁p ets ▁to ▁exit . ▁Additionally , ▁pet ▁doors ▁may ▁be ▁electronic , ▁only ▁allowing ▁animals ▁with ▁a ▁special ▁electronic ▁tag ▁to ▁enter . ▁ ▁A ▁trap door ▁is ▁a ▁door ▁that ▁is ▁orient ed ▁hor