Using a system based on standard augmented transition network (ATN) parsing approach, this report describes a technique for the rapid development of natural language parsing, called High-Level Grammar Specification Language (HGSL). The first part of the report describes the syntax and semantics of HGSL and the network implementation of each of its constructs, while the second section discusses the algorithms used in the HGSL compiler and the ATN interpreter. The third section presents a large grammar for technical prose that was developed with the system and which allows parsing of technical training materials in the draft stage of writing as part of a computer-based comprehensible writing aid. The report concludes with a review of some of the results on the coverage of the grammar. The grammar for technical training materials is appended. (FL)