No more then 10 variables?

Is it true i can only use $0 - $9?? When i use $10 i get an error compiling:

Usage: EnumRegKey $(user_var: output) rootkey subkey index

$0-$9 and $R0-$R9, if you need more, you can use: var foo, then $foo is a variable

Remember that you can also put variables/registers on the stack

Remember that all the variables you create with the Var command are global, if you declare them in a function or section you have to use the global switch: Var /GLOBAL example