This question already has an answer here:
When viewing a package on the Ubuntu repositories (e.g. launchpad), there is usually only a sentence or two describing the package contents. Is there a place online to see more detail about package contents? Often, downloading a separate docs package is the only way I can get any more info.
Responding to a comment (and other posted answers): I would like something different from listing the file names, since my question is about understanding the technical functionality provided by various packages, for example, what versions of various standards the package implements or where to find the corresponding documentation.