@User: The lowRISC guidelines are only dealing with system verilog vs. verilog and the idea of verilog header files. I agree that .v and .sv should be standard, and I'm okay with the

<filename>.<property>.v

syntax (although it immediately highlights any sloppy programming that does not look for the last occurrence of "." in a string to find the file extension). "pp" is good for "with power"; probably "tb" is good for testbenches and "gl" is good for gate-level netlists.