Sir(s),
The Conveyance Allowance paid regularly without consideration of any actual expenses is a part of wages under section 2(22) of Employees' State Insurance Act, 1948 and contribution on the same is payable as a part of wages.
However, Conveyance Charges on actual basis paid separately ( viz. by vouchers) in order to defray special expenses incurred for any travel/journey is not part of wages and no contribution on the same, in my opinion, is payable.
There appears to be no separate notification for the same since it is laid down in above Act. However, in case of any doubt, I will suggest you to take up the matter with appropriate Regional/Sub-Regional Office of ESIC of your area indicating your ESI Code No.also.
With regards;