A Checker searches the chemical structure for issues and reports the problems found.
A given molecule that has passed the checker can get two types of flags. If all of its structural features are valid, the checker marks the compound as correct. In case of a structural issue is found, the molecule is flagged as problematic.
There are a wide range of built-in Checkers supplied with Structure Checker.
See Fixers to find out how structural issues found by Checkers can be solved!