When a German public body builds a school or a road, it awards the work under the VOB/A, the standard award rules for construction. Section 15 covers the time between the opening of the bids and the award. The client may ask a bidder only for explanations, for example about whether his price is reasonable. Then the rule is plain: Verhandlungen, besonders über Änderung der Angebote oder Preise, sind unstatthaft. Negotiations, especially about changing the bids or the prices, are not permitted. The only exception covers alternative bids and bids based on a performance program. There, small technical changes may have to be agreed, and the price may change with them.