In a startup I co-founded in 2001 I invented a tooltip sub-hypertext for wiki-like website compilation of language source-code in-situ documentation and software maintenance. Initially focused on embedded software maintenance markets, the initial focus was the C-language, and a demo website of the Apache2 source code was used as proof of concept, supporting such features as inline macro expansion. Yet my longer-term goal was using it for semantic-intensive languages like MC Fortran. This image illustrates the use of a tooltip with embedded links to standard popups like this.
Standard website navigation and annotation features of the “Spiritext sub-hypertext” that were language-specific could be compiled as an extension of the language translation process. This image illustrates some of those features.
Then, after website generation, application specific annotation could be added by website viewers as permanent footnotes or temporary collaborative notes with emailed retrolinks for dialoging with callaborators.
See this link for examples of Fortran Calculus websites generated by the current Spiritext generator.