Arm just released the ASL 1.0 specification. https://developer.arm.com/architectures/architecture%20specification%20language

ASL 1.0 is a bunch of changes to the ASL language that is used both for Arm’s executable ISA specification and in Arm’s documentation.

[I contributed to the changes when I was at Arm… and when I was at Google… and also now that I am at Intel and I think 1.0 dramatically improves the language: reducing the potential for confusion and simplifying mechanised uses.]