The growing complexity of computer systems, together with the rapid evolution of hardware, has created two significant problems in Software Engineering: (1) the quality control of software, and (2) the effective communication between project participants when natural language is used to convey technical information. The aim of LESD project is to develop a set of computer tools to (a) provide a conceptual representation of aerospace software functional specifications in English; (b) evaluate traceability, consistency, completeness, verifiability, and modifiability (these constituting the main quality factors) using AI techniques; and (c) control specifications quality based on software quantitative measurement.