AML stands for ACPI Machine Language. This is a binary pseudo-code format, which the operating system's ACPI AML interpreter parses to discover the machine's properties. Since most BIOS implementers do not like to write in binary, the ACPI specification also includes ASL (ACPI Source Language). System designers describe their system in ASL. It is then compiled into AML, and included in the system's flash BIOS. Then, on boot, the BIOS startup code copies it into RAM, where it can be interpreted by the OS's ACPI AML interpreter.