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| | MARC DTD: Background and Development |
 | | SGML is a technique for representing documents in machine-readable form which was approved as an international standard, ISO 8879 (Information processing--Text and office systems--Standard Generalized Markup Language). |
 | | Due to constraints presented by the SGML standard itself, certain things had to be specified in the MARC DTDs that are not explicitly specified for MARC (ISO 2709) records. |
 | | The structure of subfield-level SGML elements would be the expected alphabetic prefix ("mrcb" or "mrca", depending upon the DTD), the three-digit numeric tag for the field in which the subfield is valid, a hyphen (-), and the one-character subfield identifier, usually a lowercase letter a-z or digits 2-8 (for example: mrcb245-a, mrcb245-b, mrcb245-6). |
| www.loc.gov /marc/marcdtd/marcdtdback.html (6353 words) |
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