Dental Recruitment What Is "Recruitment & Retention Salary" - A Term Included In A Job Ad. (bonus Pay / Value Of Salary Or ?)?

What is "Recruitment & Retention Salary" - a term included in a job ad. (bonus pay / value of salary or ?)? - dental recruitment

Working text of the ad:

Salary: $ 17.33 - $ 23.16 per hour *

Paid value of the national health insurance and dental: $ 336.80 every two weeks.
Rate for the State Employee Retirement: 19,22% of earnings.

* Includes 15% recruitment and retention salary adjustment and a premium of 5% per year training.