Hi Matt,
>
> 1. What do the double parenthesis '(( Values .... ))' mean?
Nothing, it was easier to continue typing and close one more on the phone. Single parenthesis are enough.
>
> 2. What is the 'x(field)' in the column alias?
X(field) is just to make the example more readable. And name the example table x with the column field to illustrate the main part of the example encode(yourfield, 'hex')::macaddr