Fixed Assets and Jobs provide areas for associated documents, pictures, diagrams and the like.
Typically in the "Fixed Asset Documents" section, you might add a collection of service manuals, diagrams, note templates, warranty part info & service bulletins.
In the Job "Work Order Documents" you would place diagrams and documents that help with the execution of the work.
In both cases you can make folders to help with data organization.
"Work Order Documents" will be attached to Work Orders when emailed.