The three generations
The standard has developed over decades, and all three generations are still encountered in practice. Which one is used is decided by the parties' software rather than by the standard.
| Generation | Identifier | Characteristics |
|---|---|---|
| GAEB 90 | D81 to D86 | line-oriented, fixed field lengths, no text formatting |
| GAEB 2000 | P81 to P86 | extended character sets, longer text fields, long texts |
| GAEB DA XML | X80 to X86 | XML-based, designed for automated processes and interfaces |
The XML generation is the applicable standard. Version 3.3 has been released since 2019, is progressively displacing the older formats and is designed for connection to further systems.
The older formats nonetheless disappear slowly. Anyone working with varied counterparties should expect to receive all three generations and check which their tools can read.
The exchange phases
The standard organises exchange into numbered phases. The first digit denotes the area, the second the step within it.
| Phase | Content | Direction |
|---|---|---|
| 81 | Bill of quantities | internal, as the basis |
| 82 | Priced bill by the designer | internal, with the designer's rates |
| 83 | Invitation to tender | client to tenderers, without prices |
| 84 | Tender submission | tenderer to client, with prices |
| 85 | Alternative tender | tenderer to client |
| 86 | Award and order | client to contractor |
Further areas exist alongside these phases, for instance for trading transactions between merchants and contractors. They play no part in procurement.
A note on research: the available professional literature and vendor documentation carry divergent allocations for individual phases, particularly on which phase reflects the invitation to tender and which the tender submission. The allocation given here is confirmed by several independent sources. In any given project what governs is what the participating programs produce and expect; the phase therefore belongs named on handover.
Phase 82 deserves attention
For cost planning, phase 82 is the most interesting and the least used. It carries the bill of quantities with the designer's own rates, not the tenderers'.
It therefore reflects precisely what cost planning requires at that point. That means determining costs on the basis of priced bills of quantities and cost control by comparison against the cost calculation.
Anyone using this phase obtains a cost determination structurally identical to the later tenders and therefore directly comparable. The system is covered in the article on the pre-tender estimate.
What to watch when exchanging
Four points cause most of the problems.
| Source of error | What goes wrong |
|---|---|
| The phase must match the step | an invitation-to-tender file must contain no unit rates; where prices are nonetheless transmitted, the wrong phase was chosen or the file came from the pricing system, which in a procurement procedure is a serious error |
| Item numbers must stay stable | the entire exchange rests on them; renumbering an item breaks the links between tender, order and final account |
| The structure must suit the format | levels of hierarchy, item types and text formatting are supported differently by each generation; an older format may lose formatting or long-text content |
| The version belongs named | which generation and version is expected belongs in the tender documents, otherwise queries or unusable returns follow |
The practical benefit
Three effects justify the effort of standardisation. The third is the one that carries cost control directly.
| Effect | Benefit |
|---|---|
| No re-entry | items, quantities and texts need not be re-keyed at any stage, which saves time and avoids transcription errors |
| Automated tender checking | arithmetic checking and a price comparison by individual item can be produced by machine, the only practicable route on large bills |
| Continuity through to the final account | the same structure carries from the bill through the tender to measurement, keeping the target-actual comparison available across the whole project |
The third point is economically the most significant and the least exploited. The system of cost control is covered in the article on target-actual comparison.
The boundary with the model
The standard exchanges alphanumeric data: items, quantities, texts, prices. It does not exchange geometry.
Where design proceeds from a model, two data worlds therefore sit side by side: the model with the geometry and the bill of quantities with the commercial structure. Connecting the two is the subject of separate bodies of rules and is not yet fully standardised.
In practice this means quantities are transferred from the model into the bill, and that transfer must comply with the measurement rules of the VOB/C. A quantity from the model is not automatically the one contractually owed. The system is covered in the article on BIM-based cost determination.
Related articles
This article reflects the position of the standards at the date of checking and serves professional orientation. It does not constitute legal advice and does not replace assessment of the individual case.