the first paragraph:

    As an example, say we wish to find all the records that
    are in the  temperature  range  of  other records. In
    effect, we need to compare the temp_lo and temp_hi
    attributes of each EMP instance to the temp_lo and
    temp_hi  attributes of all other EMP instances.

I believe that EMP should read WEATHER, as the example query that
follows joins WEATHER to itself.

EMP is often used in Oracle examples.

Regards,
Graham

Other RULE cleanups