TBG6 Architecture, Engineering and Construction
This specification provides the definition of the Invitation to tender message (CONITT) to be used in Electronic Data Interchange (EDI) between trading partners involved in administration, commerce and transport.
1.1 Functional definition
At the pre-construction stage of a construction project, the Client will wish to appoint a contractor to execute the works.
The first step in this appointment process is to issue an invitation to tender (ITT) to contractors this will require a commercial offer to be made by the contractor to the client.
1.2 Field of application
The Invitation to tender message may be used for both national and international applications. It is based on universal practice related to administration, commerce and transport, and is not dependent on the type of business or industry.
The following descriptions refer to the construction industry as an example, but do not exclude other business sectors' implementation.
A BoQ is a set of documentation that describes the various facets of work that make up a construction project. This documentation is often quite voluminous and typically contains information structured in accordance with several industry standards.
The BoQ is a key set of documentation for a number of stages within the overall construction process. This documentation, or parts of it, are frequently exchanged between the various parties involved in the project.
A significant document used within the invitation to tender process is the Bill of Quantities (BoQ). This documentation subsequently becomes the contractual basis for the project.
A project is typically subdivided into individual groupings of work and within these groups are detailed work items. It is down to this level of detailed work items that commercial offer information is to be supplied.
If there are any project design changes during the tender period, which have an impact on the detailed work items in a BoQ, these would also be communicated in a CONITT message.
Although the initial exchange typically takes place at the pre- tender stage, it may also be used post-tender.
At the pre-tender stage, one or more competing Main Contractors will be sent by the Client or his representative, a BoQ document for the purpose of pricing the detailed work items to support the commercial tender offer. The Main Contractors in turn may wish to invite tenders from subcontractors for specialist portions of the project. This would be done by each competing Main Contractor creating subsets of the original BoQ document for each type of specialist work and sending that in turn to a number of competing subcontractors of their choice.
Once the main contract has been established with the successful Main Contractor, the ITT process will in some cases be repeated with subcontractors. This will enable the Main Contractor to seek improved offers from subcontractors following the securement of the contract.
This is only one of a number of messages being designed for the BoQ and the principles for this CONITT message are consistent with those adopted for each of the other BoQ messages.
There are several concepts to be understood and these are key to some of the design principles adopted. Most of these have been created to respond to two base problems associated with the BoQ documentation:
i) A BoQ is often a very large document, it is not unusual for it to run to several volumes in its paper form.
ii) Given the size of the documents, there is also the problem of how to advise on the structure to which the document conforms and the accurate indexing and sequencing of information within such a volume of data.
1.3.1 Work Items
Each individual component of work referred to in the BoQ is called a "work item" and it is at this level that progress and payments are evaluated. For each work item a description is provided and this description is very precise in its wording.
This results in two things:
i) A lot of repetitive descriptions for like items at least at the higher levels within these levelled descriptions.
ii) A lot of similar work items, indeed the same description, often occurs a number of times throughout the project but assigned to different work items.
Point ii) above has been addressed by a concept called " standard items", this enables an equivalent to a standard library of descriptions to be exchanged and individual work items to reference a standard description that need be sent, only once.
Frequently within a BoQ, elements of an item's description are common to adjacent items. When this happens the items which share the same description are grouped together and the common part of the description is presented once at the start of the group. This concept is used extensively and it is possible to have quite a number of layers of shared heading.
Two distinctions need to be established, firstly, the existence of Heading text which is related to an item. There can be multiples of these as in the levels of a standard description.
The second distinction is that of "Groups". Where a group is a collection of more than one work item and all of these items have a common theme.
- they all belong to the same trade
- all for the same part of the project, building or structure.
Despite the large number of items that they may embrace, or the fact that they represent substantial parts of the project, all of these are recognised as "groups".
Thus, there can be several or many items within a group and there can be layers of groups within groups, all of which collectively constitute the project.
There are numerous variations for structuring the information that makes up the BoQ. Although, it is possible to introduce some standardisation it is clear that any message must allow the freedom to structure the data according to the dictates of a individual project. The design therefore, includes the ability to convey the document's structure as part of the BoQ message. Indeed the design allows for a different set of document structuring information, to be defined at group level as well as globally for the project. This means that a set of indexing rules can be defined to apply to the entire project and that a different set of indexing rules can be used to override these for a given group(s).
To complement the indexing concept there is a component referred to as the "Project Index Reference". This is a faceted code assigned to all items of data that are to be used in conjunction with the index. In other words all pieces of data that are to be structured using the index must contain a structured code composed in accordance with the index and this is used as a "sorting" mechanism to ensure that the data is correctly structured.
1.3.3 Message format
The actual appearance of the message bears no relation to the appearance of the current paper document.
As there are unlimited permutations for assembling the BoQ data it has not been possible, nor desirable to make the appearance similar. The CONITT appearance is similar to the results of the data analysis exercise. Namely that there are 4 blocks or groupings of data, each of which can appear many times and that all of the mechanisms for linking and relating the components together are data elements within these blocks. The task of interpreting the indexing rules and subsequently assembling the data in the message will fall to local software. The complexity of this task has been simplified by grouping the data elements into the blocks described above. In this way the processing can follow a logical flow.
This approach has several advantages over the existing rigidity of the paper document. It is clear to the message design team that BoQ documentation exchanged using EDI will deliver a variety of new opportunities to its users.
This last principle offers the solution to the volume problem too. One message has a definitive number of occurrences for each block of data. If for a "large" project this number is exceeded then multiple versions of the same message are built.
It also enables a BoQ to be exchanges in subdivisions if so desired.
See UNTDID, Part 4, Chapter 2.3 UN/ECE UNSM - General Introduction, Section 1.
3. TERMS AND DEFINITIONS
3.1 Standard terms and definitions
See UNTDID, Part 4, Chapter 2.3 UN/ECE UNSM - General Introduction, Section 2.
3.2 Message terms and definitions
Bill of Quantities - BoQ
A document that is used as the basis of a tender. It gives a description and measurement of quantities of labour and materials, and other items required to carry out a building contract. It is based upon the drawing specifications and schedules and forms part of the Contract documents.
Form of Tender
Pro-forma's that are issued by the Client's representative and used by competing contractors to submit their proposed prices.
Price Fluctuation Formula
A formal process for calculating the allowance in a contract for changes in the cost of labour and material that occur during the course of construction.
A multiplication factor applied when taking dimension information from drawings. It is used to denote the number of times a particular piece of work is repeated.
An occupation such as carpentry or bricklaying that needs a specific set of manual skills and training.
Individual components of work that are identified within a BoQ.
4. MESSAGE DEFINITION
4.1 Data segment clarification
This section should be read in conjunction with the segment table which indicates mandatory, conditional and repeating requirements.