控え: a reserve player and a copy of an application
Identify the person in 控えの選手 and the document in 申込書の控え. Compare a reserve player entering the game with a request to keep a copy until a procedure is complete.
The reserve player who enters the game
控え (ひかえ) includes reserve and copy. 「先発選手が負傷し、控えの選手が急きょ出場した。」 means “A reserve player entered the game when the starter was injured.” 控えの選手 is a person: the reserve player who entered after the starter was injured. The sentence reports entry into the game, not merely waiting.
先発選手 and 控えの選手 distinguish the roles of the two players in this sentence. The reserve player entered at short notice. This is a person’s role and action rather than a relationship between spare objects.
The copy to keep until completion
「申込書の控えは手続きが終わるまで保管してください。」 means “Please keep a copy of the application until the procedure is complete.” 申込書の控え is a copy of the application. The requested keeping concerns a document rather than a player or another person on standby.
手続きが終わるまで supplies the end condition for keeping the copy. The sentence requests retention until that point instead of reporting that the copy has already been kept. Read the document together with the scope of the request.
Use the surrounding nouns and actions
In 控えの選手, 選手 identifies a person. In 申込書の控え, the relationship to the application identifies a document copy. The accompanying noun and action distinguish the senses of the same word.
The player example contains injury and entry into the game; the application example contains a copy and a retention condition. A copy is different from a summary or excerpt, while a reserve player is different from an object held in storage.
What does 控え refer to in the player entering at short notice and in the application copy to be kept until the procedure is complete?
Show the answer and why
The first refers to a person, the reserve player. The second refers to a document, a copy of the application. Keep the completed entry into the game separate from the request to retain a copy; the copy is not a summary, excerpt, or omitted text.