In large part this classification is done automatically on the basis of descriptors in the problem title and constitutes one of the online editorial tools for exploring the database. The process of editing was further facilitated by attributing a section code to each problem. Other codes, notably F, are used for exceptional cases. During the editorial process the code attributed to a problem may be modified to position it more usefully within this pragmatic system, as well as to give it a lower editorial priority. Identification of functional relationships Just as few problems exist in logical isolation, so few are independent of each other.
Most problems aggravate some others directly, and in their turn are aggravated by others.
Some problems reduce others, or are reduced by them. This information may be present in the material collected on one problem thus enabling the relationship to be inserted. Just as with the logical relationships, the documentation may suggest functional links to other problems at a level which is too general or too specific because the database structure is already more finely articulated. Again it is a matter of editorial judgement how this is to be handled. No relationships may be indicated in the documentation, in which case it may be appropriate to insert those that are obvious.