Custom fields unique identifier

I'm looking at buying the business edition for a client.
Currently we have a php script that looks at a folder full of images and creates a table showing the images and a list of options (sizes) that they can select.
Once they have selected the product they pay via paypal.
The code creates a unique identifier for each photo i.e.

43556_6x4_colour_a1234

43556 = photo name
6x4 = size wanted
colour = colour
a1234 = unique customer id

Question is, can the custom fields be used to create a unique code such as this? If so, will definitely be buying and recommending to our other clients.

With some custom code to generate the unique code, yes, you should be able to do that with a custom field.