[Highland Park] Help in Understanding Terms on the County's Property Assessment Site

There are three terms on the County's Property Assessment Site I'm not sure what they mean. Can anyone help? The terms in the Residential Building Information section are: Grade (It has a letter grade), What is it grading and what do the letter grades mean? Condition (it has terms like fair, average, etc) I assume that the terms refer to the shape of the building. Garage ( I see mostly "0" listed where there are garages on the property) Does this only refer to integral garages? Thanks, Ed Sullivan