信しん号ごう書しょ

noun

signal code book

A book containing signal codes, used in contexts such as maritime, military, or railway communication.

• 船せん長ちょうは信しん号ごう書しょを参さん照しょうして旗はたの意い味みを確かく認にんした。

  The captain consulted the signal code book to confirm the meaning of the flags.