The call for reusability, interchange, system- and software-independence, portability, and collaboration in the humanities was answered by the advent of the Standard Generalized Markup Language (SGML) which became an ISO standard in 1986 (ISO 8879: 1986) (Goldfarb, 1990). SGML is not itself a markup scheme, but a methodology that enables the creation of such schemes. Based on IBM’s Document Composition Facility Generalized Markup Language, SGML was developed mainly by Charles Goldfarb to become a metalanguage for the description of markup schemes that satisfied at least seven requirements for an encoding standard:

1. The requirement of comprehensiveness;
2. The requirement of simplicity
3. The requirement that documents be processable by software of moderate complexity;
4. The requirement that the standard not be dependent on any particular set or text-entry devise;
5. The requirement that the standard not be geared to any particular analytic program or printing system;
6. The requirement that the standard should describe text in editable form; and
7. The requirement that the standard allows the interchange of encoded texts across communication networks.

Such a markup scheme was exactly what the humanities were looking for in their quest for an encoding standard for the preparation and interchange of electronic texts for scholarly research.