Function application_ranks 

pub fn application_ranks(tier: MatchTier, weight: FieldWeight) -> Option<i32>

What a tier earns in an app’s fields: an app is found by the words that name it begun, never by a word that merely holds them. A typo, words spread over its fields, or the query inside a longer word each find half the catalogue (“nodes”, “note pad”, “footnotes”), so an app row needs a word it is named by to start with what was typed — its name, an alias, its kind. Inside those fields an app’s keywords are its other names (Finder and Explorer are Files, Task Manager is System Monitor), so a keyword typed whole or begun ranks like the start of its name: “explo” is already Files, ahead of every file that merely starts with it.