$ 0, $ 1, $ 2, $ 3, $ 4, $ 5, $ 6, $ 7, $ 8, $ 9, $ R0, $ R1, $ R2, $ R3, $ R4, $ R5, $ R6, $ R7, $ R8, $ R9
registers. These variables can be used as custom variables, but are commonly used in general functions or macros. You do not need to declare these variables, so you will not get any name conflicts when they are used in common code. When using these variables in common code, it is recommended that you use the stack to save and restore their original values. These variables can also be used to communicate with plugins, because they can be read and written via pluggable DLL files.