"[!Exact !search !volume]"
Search volume in the format where number of words in a keyword, their word forms, and order are specific and fixed. I.e. "[!this !exact !keyword !form]". This data is very important, as it allows to filter irrelevant keywords. Most services do not check this data, as checking them is much more expensive compared to checking broad and precise (only specified words, but in any order and form) search volume.