using FUNCTION instead of CREATE FUNCTION oracle pl/sql -

I see that instead of the function, write the function to people with FUNCTION "Creating functions" when I see this experiment in the web I thought it was a typo or something but in Orelli's "Oracle 11GPL / SQL Programming" Steven Fearnstein used the same thing to the author. But when I execute it, I get errors. Can anyone explain it to legal use or not? Thank you.

It depends on context.

To create a standalone function, you create functions ... or create or redo function ... .

To declare a function within a package or type of body, you can use the function ... .

will use create keyword as an order, the function is the type of object that can be made.

Usually CREATE is omitted because one function can be specified in many different ways, and there is no need to calculate them all.