18. In this Part—
“claim” means a claim in accordance with Part 4 of these Regulations for an amount of credit arising under this Part and “claimant” shall be construed accordingly;
“customer” means a person for whom a taxable activity is carried out by the claimant;
“outstanding amount” means, in relation to any claim—
if at the time of the claim the claimant has received no payment in respect of the amount written off in his accounts, the amount so written off; or
if at that time he has received a payment, the amount by which the amount written off exceeds the payment (or the aggregate of the payments);
“relevant disposal” means any taxable disposal upon which a claim is based;
“security” means—
in relation to Scotland, any security (whether heritable or moveable), any floating charge and any right of lien or preference and right of retention (other than a right of compensation or set-off); and
in relation to England, Wales and Northern Ireland, any mortgage, charge, lien or other security.