In March of 2017, Independent Book Publishers Association (IBPA) introduced an industry standards checklist for professionally published books. In the introduction to the checklist, IBPA states,
The purpose of this checklist is to give both authors and industry professionals an at-a-glance gauge of the professional presentation of any book. It must be acknowledged that book development is a creative process and that quality can be subjective. This list does not address editorial content except to recommend that any book be professionally edited (developmentally edited, copyedited, and proofread). To meet professional standards, any book should be grammatically accurate and free of spelling and typographical errors. This checklist is broken into two sections: (1) Content and (2) Production.
This is the checklist our presenter in February, Lee Wind, mentioned.
In addition to a downloadable version of the checklist, the IBPA website provides a number of other resources including samples of covers, inside book design, title pages, and copyright pages, all provided with the permission of the sources.