The Book of Precedents is one of the Ai-Naidari Books of Civilization. It has volumes for different castes and contains information on behavior that applies to all individuals (generalized relationships, such as the duties of parents and children, people with responsibility over others, heads of households, the proper treatment of the elderly and infirm, etc.) This book also contains legal rulings that created historical shifts in those duties.
Random[]
I check the Book of Precedents and flatten out a page for you to see; while it doesn't cover the behavior of aunera, of course, it does suggest that from beneath the Wall of Birth to above it, such sympathies can be tendered several days later in the form of a small ephemeral gift, such as (of course) flowers. No note should be included, though a card with the sender's name is permitted.
The Regal Volume[]
The Noble Volume[]
There is a section on the proper behavior toward merchants. Many pages are devoted to describing many forms of esar.
The Public Servant Volume[]
The Guardian Volume[]
The Merchant Volume[]
There is a section detailing the expected behavior between nobles and merchants, beginning with the fact that a noble may touch a merchant on any part of his body without permission. A merchant is allowed to refuse a noble only in matters of his trade... nothing else.