回美證 I-131疑問,請各位幫忙 - 移民

我在看移民局關於申請回美證的指示時,看到一項說明

A permanent resident alien who intends to remain abroad for more t
han a year should, at least 30 days prior to the proposed date of departure,
apply while in the United States to the U.S. Citizenship and Immigration
Services (USCIS) in the Department of Homeland Security for Reentry Permit.

也就是說要在離開美境的30天內提出申請,
但是之前爬文也看到版友們提到提出申請之後就可以離境,
想請問哪一個說法是正確的呢?
或還有沒有要等哪份文件或收據拿到後才能離境??
由於牽涉到找工作的時間問題,我急於釐清此項要求
請各位有經驗或有相關知識的朋友幫忙, 謝謝!!!

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