1. A computer-based system for monolingual document development, comprising: a text editor adapted to accept interactively from an author input text written in a source language; a language editor, which is an extension of said text editor, which interactively enforces lexical constraints and grammatical constrains on a natural language subset used by said author to create said input text, wherein said author is interactively aided in enforcing said lexical constraints and said grammatical constraints on said input text so as to produce unambiguous constrained text; a machine translation system, responsive to said language editor, that is configured to translate said unambiguous constrained text into a foreign language; and a domain model, which communicates with said language editor, wherein said domain model provides pre-determined domain knowledge and linguistic semantic knowledge about lexical units and of their combinations, so as to assist said language editor in said enforcement of said lexical and grammatical constraints wherein said domain model is a tripartite domain model, said tripartite domain model comprising, a kernel which contains lexical information that is required by said language editor and said machine translation system, wherein said lexical information includes lexical items within a natural language subset along with associated semantic concepts, parts of speech, and morphological information; a language editor domain model which contains information that is required only by said language editor, wherein said information includes at least one of a natural language subset of synonyms for items not within said natural language subset, a dictionary of definitions of said lexical items, and a set of examples of using said lexical items, and a machine translation domain model which contains information which is required by only said machine translation system, said machine translation domain model includes a hierarchy of concepts used by unambiguous mapping and semantic verification in translation.