The Boost.Build v2 User Manual has several references to a project-root.jam file, but never explains what this file is or what is supposed to go into it.  Is it just an alternate name for the Jamroot file?  If not, how does its function differ from Jamroot?

In addition, several of the examples included with Boost.Build v2 include both a Jamfile and a project-root.jam, but no Jamroot; examples/gettext is one of these.  Why two separate files?

Finally, if project-root.jam and Jamroot are just different names for the same file, then is this line in kernel/errors.jam wrong?

local user-modules = ([Jj]amfile(.jam|.v2|)|user-config.jam|site-config.jam|project-root.jam) ;

That is, should [Jj]amroot be in there too?