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A general description is here.
A new dynamic HTML help system is used by default, and may be controlled using tools::startDynamicHelp(). With this enabled, HTML help pages will be generated on request, resolving links by searching through the current .libPaths(). The user may set option("help.ports") to control which IP port is used by the server.
pbeta(x, *, log.p = TRUE) is sometimes more accurate, e.g., for very small x.