All documents in the repository are valid in relation to a specified contract area (or areas), which is a defined term in most contracts. Sometimes this may be a whole concession block, or more than one block, as in an Exploration and Production Agreement. Sometimes contractual documents are more narrowly defined to a particular producing field or area within a concession block. Concession blocks can also be divided over time, with a resulting forking of contractual documents. For example Concession Block 3 could be awarded to Company A which makes a commercial discovery within it. At a given trigger point in the initial exploration and production contract, the company defines a production area. The company may be obliged to relinquish other parts of the block after a given period of time, at which point a part of the original concession area is then bid out as a new concession block and awarded to Company B. There is no globally standardised renaming convention in such cases. The remaining part of the initial concession area could still be known as Block 3 despite now having a different geographical extent to the original, or it could be called Block 3/A, and the second concession block known as Block 3/B. Also, it is not uncommon once a concession area has yielded a commercial discovery in a field with a particular name for the name of the block and the field to be used interchangeably, or both together, when referring to contractual documents.