Sony has used the Z model naming scheme for its high-end ultraportable notebook computers since 2000. Unlike other Sony models, the Z has always been manufactured in Japan or in the United States for some models (i.e. VGN-Z540). Sony has stated that production of the Z series will cease at the end of 2012. The model numbers for these computers have been PCG-Z (2003), VGN-Z (2008), VPC-Z1 (2010), VPC-Z2 (2011), SVZ (2012). For differentiation, subsequent Z models proceeded to include high-end screens, CPUs, GPUs and on-board DVD/Blu-ray drives etc.