The four forms of discrepancy
| Form | What happens | Consequence |
|---|---|---|
| Item without prescription | the bill lists work the specification does not describe | undetermined content, arbitrary pricing |
| Prescription without item | the specification describes work absent from the bill | unpriced work, likely dispute |
| Divergence of content | the two contradict each other on the same work | interpretation required |
| Divergence of unit | the bill's unit does not match the description | wrong or incomparable quantity |
The first two are the most frequent, and the second is the costliest. Work described but not priced will be carried out and invoiced, in a balance of power without competition.
Where they come from
Three causes, and none amounts to individual negligence. They relate to the tools, the versions and the production chain.
Reversed drafting order. Where the bill is taken from an earlier project and then supplemented, it does not derive from the selection of prescriptions. The two documents then have different origins, and their consistency is merely hoped for.
Project iterations. Projects evolve. Each change potentially touches both documents, and a change applied to only one creates a discrepancy that will survive to tender stage.
Separation of media. The text lives in a word processor, the quantities in a spreadsheet. Nothing links an item to the article describing it, and nothing flags that an added line has no corresponding prescription.
What the official documentation says
This point deserves citing, because it comes from the publisher of the framework itself. The recommendation appears in the note accompanying publication.
The note accompanying publication of the Walloon framework recommends drafting particular specifications in a tool based on a database linking prescription texts to bills of quantities, in order to avoid omissions and discrepancies between documents. The recommendation aims to avoid double entry.
It states that using a word processor together with a spreadsheet is not recommended, because it imposes additional checks of consistency between prescriptions and bills. Double entry is indeed the primary source of inconsistency.
It is an observation of method, made by the administration that publishes the framework. It does not say office-based working is impossible; it says it shifts the burden of consistency onto a manual check.
Prevention methods
Four approaches, workable whatever the tooling. They run from manual checking to an integrated tool.
Derive the bill from the selection, never the reverse. That is the rule set out in the article on using the CCTB, and it is the most effective.
Use the index as the key. Each item in the bill carries the index of the corresponding element. An item without an index stands out immediately, and so does an index without an item.
Check in both directions. Verify that each item has a prescription, then that each selected prescription has an item. The second check is the one that gets forgotten.
Repeat the check after each iteration, not once before issue. Discrepancies arise from late changes.
The cross-check in practice
A simple method, applicable even on a spreadsheet. It rests on cross-checking the indexes cited.
Extract the list of indexes cited in the bill on one side, the list of selected elements on the other, and compare the two. Gaps one way reveal orphan items, gaps the other way reveal unpriced prescriptions.
That operation takes little time and catches most structural discrepancies. It does not catch divergences of content, which require reading.
The articles in this branch
The article on measurement errors covers consequences and who bears them. The commonest errors are listed there.
The article on the annual update covers changes of version mid-project. Its documentary consequences are explained there.
The article on measurement, BIM and coding covers attaching quantities from a model. The link between model and bill is covered there.
The article on checking a third-party bill gives an eight-point method. The checking method is described there step by step.
This article reflects principles of professional practice at the date of checking and serves as orientation. It does not constitute legal advice and does not replace consulting the applicable framework.