Explanation
PerfectIt checks to see if an abbreviation appears before it is first defined.
It suggests there may be a possible issue if there is a definition but the abbreviation appears elsewhere in the text before it.
The suggestions list shows all the uses of the abbreviation that occur before the definition and the location where the abbreviation is defined.
Suggestion
If the author chooses to define an abbreviation, it should be introduced in the first instance with either the abbreviation or definition in parentheses.