GEC Software was based in London, UK. The division I worked for produced an integrated development environment called TenPlus. This environment was based on the concept of a tree structure, starting from a directory root, navigating through several sub-directories, opening a file, then exploring sections and sub-sections of that file. It could be configured to navigate differently depending upon context. For example, a text document could be broken up into sections, chapters, and paragraphs, whereas a C code file could be broken up into functions.
I did a miscellany of tasks with TenPlus from July to September 1988. The most interesting was to attempt to model TenPlus within itself. I also wrote several extensions to TenPlus in C.