What is usage of _queryMatch(cmdbci3, rule, sourceField) in CI Lookup Rules and how _queryMatch work

[Sangeetha6]

Hi Team,

I am trying to understand CI lookup rules, could you please help on the following,
What is usage of _queryMatch(cmdbci3, rule, sourceField) in CI Lookup Rules and how _queryMatch work?

Regards,
Sangeetha