It is good practice and highly recommended to fill in the<unk>  field, or add to it in the case of section<unk> ing, as it helps you and your fellow contributors to understand what is changed, such as when perusing the history of the page. It's a good idea to set your user preferences (under<unk>  to "Prompt me when entering a blank<unk> ".
Edit summary
Overview template
Chapter checklist
Incident report
Algorithm
Classification template
Compiled template statements
Microbiology template