Makevars and Makeconf sequencing

http://cran.r-project.org/doc/manuals/R-exts.html#Configure-and-cleanup
near the start of 1.2.1 Using Makevars says

There are some macros which are set whilst configuring the building of
R itself and are stored in R_HOME/etcR_ARCH/Makeconf. That makefile is
included as a Makefile after Makevars[.win], and the macros it defines
can be used in macro assignments and make command lines in the latter.

I'm confused.  If Makeconf is included after Makevars, then how can
Makevars use macros defined in Makeconf?

Or is the meaning only that a variable definition in Makeconf can be
overridden in Makevars?

Ross Boylan