Vladimir, saw your 64-bit example

There's also lower-level, possibly more flexiible, configure.builds, see example at:

Please forgive my lack of understanding! Could you explain or point me to docs re what is happening in the jamroot:

    obj 64 : 64.cpp ;
    explicit 64 ;

I don't see a 64.cpp file in github

    if [ configure.builds /libraries//64 : : 64-bit ] {

what is happening here please?