The cornerstone of the BIS and written by the owner, the letter of invitation (LI) is addressed to the potential bidders, inviting them to submit their bids and briefly stating: [104]

• Plant location and main site characteristics (e. g. condenser cooling water method required)

• Contracting approach and scope of supply (base scope and options)

• Whether or not financing is to be arranged by the bidder

• Project scheduling forecast, and bid preparation and submittal schedule

• List of BIS documents enclosed with the LI

• Key BIS aspects that may be of special import to the owner and subject to special care from the bidders

• Request that the bidders formally notify, in writing and before the indi­cated date, of their intention to bid.

The LI should be brief (2-3 pages maximum) and avoid indicating details that are already covered in other BIS documents.