References are crucial, so you must include referee details on your CV. (Referees are the people who provide references).
Do NOT include the words “On Request” anywhere on your CV.
Employers have hundreds of applications and CVs to go through, they are not going to stop to call your referees, or to verify your work history prior to a certain year.
It’s just laziness and bad writing- either include the work history or don’t, but do not type “work history prior to 2009 (or whatever year) available on request.”
What probably happens is the CV writer realises they are running out of space and doesn’t know how to condense work history and group appropriate jobs together, so the easy fix is to make it the employer’s job to source the information – which is so wrong!
It’s the candidate’s job to provide the employer with ALL of the content, so they can make an informed and easy decision.
I am seeing this disturbing trend more and more. Please check your CV, especially if someone else wrote it for you, and make sure it does not include this line.