godan verb (-ku), transitive verb
Rare kanji forms 披く and 展く are used for the same meaning as 開く (ひらく). 披く often implies opening something like a book or letter, while 展く suggests spreading out or unfolding. In modern Japanese, 開く is overwhelmingly preferred.
古い手紙を披く。
Open an old letter.
Spread out a map.