RE: [] or ? for optional

[Michael Fitzgerald <mike@wyeast.net>]

Either [...] or (...)? works for me. Both are clear to me. A half line in
the spec indicating your intended meaning of either syntax will make it
sufficiently clear. -Mike

-----Original Message-----
From: James Clark [mailto:jjc@jclark.com]
Sent: Monday, July 09, 2001 7:53 PM
To: Murata Makoto; relax-ng@lists.oasis-open.org
Subject: [] or ? for optional




--On 10 July 2001 09:38 +0900 Murata Makoto <mura034@attglobal.net> wrote:

> James Clark wrote:
>
>> > - Isn't the type attribute optional for <value>?
>>
>> Yes.  There's a "?" following the attribute value that is intended to
>> indicate this. Is there some way I should fix the notation to make this
>> clearer?
>
> Sorry, I looked over the "?".
>
> I prefer "[" and "]" probably in a big font.

That would be more visually obvious, but I wonder how familiar the use of
[] for optionality would be to our potential audience. Let's do a little
poll.

If you read this, please send a message to the list saying whether you are
familiar with the use of [] for optionality and would guess that the square
brackets in

<value [type="NCName"]>string</value>

indicate that the attribute is optional.

Alternatively we could try to make it harder to miss the ? by adding
parentheses

<value (type="NCName")?>string</value>

James



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