--> context-var . field-name -->

    The name of a field in the database that consists of a context
    variable and a field name. A context variable is a temporary name
    that you associate with a relation. You define a context variable
    in a record selection expression.

    For example:

    FOR E IN EMPLOYEES PRINT  E.LAST_NAME
        |          |         |           |
        |          |         +-----+-----+
        |          |               |
      context   relation          database
      variable   name               field