No, the 'attribute' feature allows you to specify a set of 'fixed values', then when uploading an item, you can select which of the attributes apply. For example, 'color' would be an attribute, and you would setup your color attributes to have values of red, white, blue, green, black.  Then when uploading an item, the user will see the list of available values for the color attribute and be able to select which one(s) apply.

So in your case, you would not be able to use attributes to store a variable string such as a product reference. What you need is the ability to specify a custom field which does not exist in the current version. Your other option would be to re-use one of the existing fields. For example, if you were not using the 'Summary' field, you could change the text prompt on the form to say 'Product References' and then the user would be able to enter any alphanumeric string into the field. The value would be stored in the Summary field, but on the form it would look like a product reference field.