I do recommend against using punctuation in IDs. Besides some of them being used in URLs, some are used as operators or punctuation in GAME Code. Also, their use will not be as intuitively obvious as letters. For example, I had no idea what the caret meant.
I think the tilde (~), apostrophe ('), and accent (`) are probably available, and I'm sure the period and comma would be; I'm kind of afraid to try to quote ("), though it'd be perfect for Berolina.
The apostrophe is also a single quotation mark, and in that capacity, it should be considered unavailable, along with the double quotation mark. Both are used to demarcate strings in both GAME Code and PHP. The period is used in GAME Code to separate array elements from parent arrays in array element variable names.
I do recommend against using punctuation in IDs. Besides some of them being used in URLs, some are used as operators or punctuation in GAME Code. Also, their use will not be as intuitively obvious as letters. For example, I had no idea what the caret meant.
The apostrophe is also a single quotation mark, and in that capacity, it should be considered unavailable, along with the double quotation mark. Both are used to demarcate strings in both GAME Code and PHP. The period is used in GAME Code to separate array elements from parent arrays in array element variable names.