3.3 But difficult issues about how to apply Private Finance principles in practice had to be tackled. A school of thought in Private Finance at that time was that purchasers should specify their requirements at high level so as not to stifle the scope for bidders to innovate in proposing solutions. This influenced the approach of the purchasers in specifying their requirements and relying on the expertise of bidders to understand the detail and devise workable solutions. For example, notwithstanding the customer service requirements highlighted in paragraph 2.20, the purchasers did not see it as their role in a Private Finance arrangement to document the detailed rules for benefit payment in the form to be automated. Nor did they request from the shortlisted bidders, to the extent they would have done on a conventional project, details of the resources the bidders would employ on the project. Another issue was uncertainty about the extent of risk transfer that bidders would accept. Precisely how the risk of fraudulent use of payment cards was to be allocated between the Department, Post Office Counters Ltd and Pathway became a major issue only in the final stages of the procurement, and it effectively ruled out two of the three bids.