How to create a pl/sql query in the specified revision?

Good day. Just learning PL/SQL. There is some puzzle in her mind the wording:

Write a query in PL\SQL <...> in the specified revision, later specified date

I can not find on open spaces as indicated revision in the request.

Thank you.
April 3rd 20 at 17:25
1 answer
April 3rd 20 at 17:27
Not specified. In this case, meaning that the query must not contain functions and code structures added in later versions of the language.
Roger, thank you. - johan_Roob55 commented on April 3rd 20 at 17:30

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