The TTX file format, standing for Trados TagEditor, is a proprietary bilingual file format developed by SDL (now part of RWS) for use with their legacy software, SDL Trados TagEditor. It is primarily used in the translation and localization industry to store source text alongside its corresponding translation, while preserving the original document's formatting and structural tags. The format uses XML-based markup to encapsulate the text segments and metadata, ensuring that translators can work on the content without accidentally corrupting the underlying code or layout of the original file. By separating the translatable content from the formatting tags, TTX allows for efficient translation memory matching and terminology management. Although it has been largely superseded by the industry-standard XLIFF format in modern versions of SDL Trados Studio, many legacy translation projects still rely on TTX files for compatibility with older workflows and specific client requirements. It serves as a bridge between various source formats like HTML, XML, and SGML and the translation environment.