For instance, how a porch typically attaches to a house. Or how a roofline accommodates an addition. Or how gable ends are usually trimmed. This house was built 100 years ago, yet it was built 100 years after Federal Style was current. So even in its day, it was a revival of an older style.
Styles can come and go and come back again in architecture as they do in fashion.
When working with a building of an older style, it is important to think through your attitude towards the original work. It helps to differentiate between the letter of the style, and the spirit of the style. Following the letter of the style involves reproducing the exact qualities of the existing work. These materials and processes are no longer standard practice and may be attainable only at considerable effort and exorbitant cost. Following the spirit of the style requires compromise.