Subscript with parenthesis

[Tom Alexander]

The org-mode documentation[1] states that the SCRIPT portion of the 
subscript/superscript is either an asterisk, the standard set of objects 
wrapped in balanced curly braces, or an optional sign followed by "Either the 
empty string, or a string consisting of any number of alphanumeric characters, 
commas, backslashes, and dots"

But I'm seeing the following test document parse as containing a subscript 
despite using parenthesis which I do not think matches any of the above 
criteria:
```
foo_(bar)
```

[1] https://orgmode.org/worg/org-syntax.html#Subscript_and_Superscript

--
Tom Alexander