The current standard of SystemVerilog is published by the IEEE and Accellera, an industry-based standards association. It is given the number 3.1a, which indicates that it is the third major revision of Verilog. These are the SystemVerilog and Verilog standards.
This is the LRM. This, however, only defines the extensions to the Verilog standard— 1364-2005. To get a full definition of SystemVerilog, both LRMs are needed.
This is the latest standard for Verilog. There was also a 2001 version, but the changes are relatively minor.
The original Verilog standard. Most of the open source tools conform only to this standard. ...