The s390 version of
as supports two architectures modes
and eleven chip levels. The architecture modes are the Enterprise System
Architecture (ESA) and the newer z/Architecture mode. The chip levels
are g5 (or arch3), g6, z900 (or arch5), z990 (or arch6), z9-109, z9-ec
(or arch7), z10 (or arch8), z196 (or arch9), zEC12 (or arch10), z13
(or arch11), and arch12.