Default is to acquire all architectures from APT::Architectures which
can be changed by arch=, but this isn't very flexible if you want
"mostly" the default as you have to hardcode the architectures then,
so arch-= and arch+= can be used to add/remove architectures from the
On a machine with 'amd64' and 'i386' configured the lines:
deb [arch+=armel] http://example.org/debian wheezy rocks
deb [arch-=amd64] http://example.org/debian jessie rocks
will result in the download of:
wheezy Packages for 'amd64', 'i386' and 'armel'
jessie Packages for 'i386'