BASIC 65 Variable section in Appendix B implies Variables may only be alpha-numeric

[CTalkobt]

Describe where we can find the problematic topic
Currently, the following text exists in Appendix B of MEGA65-Book: "Variable names must start with a letter, and contain only letters and numbers." This is false. Variable names must start with a letter, however the second character can be a symbol, @, letter or numeric.

Describe the solution you'd like
Indicate the range with a suggested preferance to alpha-numeric and comment that @ is reserved, but not prevented for future use.

Describe alternatives you've considered

Additional context
I have attached a patch. Feel free to correct wording etc as you see fit - English sometimes feels like a second language when it comes to documentation for me.

(Patch Updated below)

[dansanderson]

Arbitrary variables with @ as the second character are not just recommended against, they're disallowed. We should probably just make them a syntax error when not referring to a system variable. I'll look into that, and then we can adjust the docs similar to what you propose (i.e. document that it's a syntax error).

[CTalkobt]

I've updated the patch to remove all references to @ leaving them undocumented. When/if they are restricted code wise it should require no changes to the documentation.

variable_names.patch.txt