XL is the library which my later RISC OS software is built on. It includes Draw file rendering and the CScript language.
In 1988, when what was to become RISC OS was called Arthur, we built programs using Acorn's 'wimp' library and used the FormEd template editor. Arthur was not a multitasking operating system (but the functions from then lived on). We had the library in source code form.
Around 1989, Acorn gave developers a new library "RISC OS Lib" this was based on the previous wimp library but included a lot more higher level material. I converted my current project at the time (Ovation) to the new library one weekend, and converted it back the next week when it became apparent Acorn would not fix the bugs in RISC OS Lib. With no source code I could not fix them either. Later RISC OS Lib was made available as source code.
I continued using the wimp library until I commenced work on Ovation Pro at the end of 1992. After five years I knew what I wanted in a library for RISC OS and created my own. I called the library XL - not a very good choice of name, but it was purely for my own use. I had published a library for Pascal some years before written by Nick Smith called 'xlib' which makes the name even less inspired.
Building the library results in an Acorn library file called "TaskLib" (not an application). For use with my other source code the whole library folder should located as $.XL (and not $.XLRel).
XL RISC OS source code