guides

Short explanations of the things the catalogue names but never defines. Every claim on these pages is derived from the published data, not written around it.

70° and 90° explainedWhat the number at the end of a configuration name means, what else changes between the two angles, and every pair listed side by side.
installation, step by stepAll fourteen steps of the D228 installation manual, transcribed verbatim, with the intended uses and standards from its certificate page. The PDF stays authoritative.

Single terms are defined in the glossary; the drawings and declarations of performance live on documents.