Oracle Query - &&# variables from SQLPlus

Question

I have successfully used &&1, &&2, &&3, etc. in my SQLPlus query, and was wondering if it is possible to use this with any Oracle query, not just through SQLPlus?
What are these "variables" properly called?

Answer 1

These are called, Substitution Variables. They are only for sqlplus. See reference documentation If you are referring to "other queries" such as withing PL/SQL, those use bind parameters.