When developing a database from such a standard, it is normal practice to prepare a data dictionary. This is a document which sets out all of the data fields that make up a computer record and specifies what information may be recorded in each field, including the reference data lists to be used and any other rules (for example the use of abbreviations). Data dictionaries have been developed for HERs. In 1993 ''Recording England's Past: A Data Standard for the Extended National Archaeological Record'' (''RCHME'' and ACAO 1993a) was published and in 1997, SMR '97 (RCHME) was circulated in draft. ''SMR '97'' provided the basis from which the ExeGesIS SDM Ltd's SMR software was developed and has continued to be developed to provide the data dictionary for that software. A range of different computer systems is in use across the UK and HER managers are recommended to make sure that a data dictionary specific to their system is available as a reference aid.
Looking beyond the physical data structure of HER databases, a complex range of information is available about the local historic environment, its investigation and management and the sources of information. HER professionals must decide how to organise that information into computer records. This manual gives some general illustrations of the issues involved in this process but it is possible to include only a limited number of case studies. HER managers. are recommended to use this as a base to develop local recording-practice guidelines for recording particular monument classes in their area, for example, Roman roads, medieval historic towns, 19th-century industrial complexes.
Data dictionaries and recording-practice guidelines are a helpful coaching aid for new members of staff or volunteers. These documents also provide useful points of reference as people are learning how to record information in the HER's computer system. They are part of the Recording Manual (see section B1: policy and Planning)