* 定義

[FIG[
[3] 
>
:"MAY":
This word or the adjective "OPTIONAL" means that this item
is truly optional.  One vendor may choose to include the
item because a particular marketplace requires it or
because it enhances the product, for example; another
vendor may omit the same item.

[FIGCAPTION[
[CITE@en[RFC 1123 - Requirements for Internet Hosts - Application and Support]] ([TIME[2010-07-22 04:07:59 +09:00]] 版) <http://tools.ietf.org/html/rfc1123#page-11>
]FIGCAPTION]
]FIG]

[FIG[
[5] 
>The key word "OPTIONALLY" in
the normative parts of this document is to be interpreted with the
same normative meaning as "MAY" and "OPTIONAL".

[FIGCAPTION[
[CITE@en[Web Applications 1.0 r6966     Allow browsers to bail early for showModalDialog, alert, confirm, and prompt during pagehide, beforeunload, and unload events.]] ([TIME[2012-02-07 07:54:00 +09:00]] 版) <http://html5.org/tools/web-apps-tracker?from=6965&to=6966>
]FIGCAPTION]
]FIG]

* メモ

[1]
[CITE@en[XML Query (XQuery) Requirements]] ([CODE[2007-03-17 06:39:09 +09:00]] 版) <http://www.w3.org/TR/2007/NOTE-xquery-requirements-20070323/#terminology-may>
([[名無しさん]])


[2]
[CITE@en[XML Query (XQuery) 1.1 Requirements]] ([TIME[2007-03-16 09:42:40 +09:00]] 版) <http://www.w3.org/TR/2007/WD-xquery-11-requirements-20070323/#terminology-may>
([[名無しさん]])



[4] [CITE@en[Web Applications 1.0 r6966     Allow browsers to bail early for showModalDialog, alert, confirm, and prompt during pagehide, beforeunload, and unload events.]]
( ([TIME[2012-02-07 07:54:00 +09:00]] 版))
<http://html5.org/tools/web-apps-tracker?from=6965&to=6966>

[6] [CITE@EN[W3C XML Schema Definition Language (XSD) 1.1 Part 2: Datatypes]]
( ([TIME[2012-04-05 06:34:51 +09:00]] 版))
<http://www.w3.org/TR/2012/REC-xmlschema11-2-20120405/#dt-may>

[7] [CITE@EN[W3C XML Schema Definition Language (XSD) 1.1 Part 1: Structures]]
( ([TIME[2012-04-05 06:34:07 +09:00]] 版))
<http://www.w3.org/TR/2012/REC-xmlschema11-1-20120405/#intro-terminology>

[8] [CITE@EN[XPath and XQuery Functions and Operators 3.0]]
( ([TIME[2014-04-08 07:02:07 +09:00]] 版))
<http://www.w3.org/TR/xpath-functions-3/#may>