Clarify whether // in an s-expression is an operator or the beginning of a comment

[zslayton]

ion-java and ion-c both fail to parse this input:

(a // b)

I would expect this to be an s-expression with three symbols:

• a (an identifier)
• // (an operator)
• c (an identifier)

From the spec's symbols section:

Within S-expressions, the rules for unquoted symbols include another set of tokens: operators. An operator is an unquoted sequence of one or more of the following nineteen ASCII characters: !#%&*+-./;<=>?@^`|~ Operators and identifiers can be juxtaposed without whitespace:

From the spec's symbol representations section:

Operator: an unquoted sequence of one or more of the following nineteen ASCII characters: !#%&*+-./;<=>?@^`|~ Operators can only be used as (direct) elements of an S-expression. In any other context those characters require single-quotes.