It is for generating an original invoice, or for amending an invoice previously sent, after the buyer has purchased the item and then contacted the seller to ask for local pick up rather than shipping.

When I see that buyers are "local" I include local pick up / 0.00postage as a second shipping option afterfirst shipping option (Australia Post parcel post parcel in my case) - the second shipping option can be added by clicking on "add another" under the first shipping option which has been selected when making the listin, and a drop down menu will appear. The buyer then sees both shipping options on their invoice. Sometimes, however, buyers from interstate contact me and ask for a local pick up invoice, which is initially a surprise, until they tell me that they are flying to Perth soon to visit relatives or on business...