# Definition DIFO

This [test](.) is exercising the definition [DIFO](../../difo/Readme.md).

### Description

In this test, the sequence of characters `¦¦` is used as *free operator*. It satisfies `DIFO` because even though `¦` is a *special symbol* (used in symbolic forms of *across loops*), it is also a *predefined operator* (hence satisfying condition 3) and an *operator symbol* (hence satisfying condition 2), and the sequence of characters `¦¦` is not a *special symbol*, a *standard operator* nor a *predefined operator* (hence satisfying condition 1).
