Permitted chars in variable name?

[apps]

I found that I can't name a variable
1variablename, that is, can't use a number as first letter.

Is there any reference for permitted combinations in variable names?

[Guerric]

Not to my knowledge. You can try searching through:
http://wiki.developer.mindtouch.com/DekiScript

Otherwise steve would know best. If I had to guess, the conventions are probably similar to that of any programming/scripting language. No funky chars (@#R&$(*), no operators, and variables must start with a non-numerical char.

[SteveB]

Variables must begin with a letter or underscore and can then be followed by letters, underscores, and digits.