Editing Reserved word (section)

==Further reservation==
Beyond reserving specific lists of words, some languages reserve entire ranges of words, for use as private spaces for future language version, different dialects, [[compiler]] vendor-specific extensions, or for internal use by a compiler, notably in [[name mangling]].

This is most often done by using a prefix, often one or more [[underscore]]s. C and [[C++]] are notable in this respect: C99 reserves identifiers that start with two underscores or an underscore followed by an uppercase letter, and further reserves identifiers that start with a single underscore (in the ordinary and tag spaces) for use in [[file scope]];<ref>C99 specification, 7.1.3 Reserved identifiers</ref> with C++03 further reserves identifiers that contain a double underscore anywhere<ref>C++03 specification, 17.4.3.2.1 Global names [lib.global.names]</ref> – this allows the use of a double underscore as a separator (to connect user identifiers), for instance.

The frequent use of a double underscores in internal identifiers in Python gave rise to the abbreviation ''dunder;'' this was coined by Mark Jackson<ref>{{cite mailing list |first=Mark |last=Jackson |date=September 26, 2002 |title=How do you pronounce "__" (double underscore)? |mailing-list=python-list |url=https://mail.python.org/pipermail/python-list/2002-September/155836.html |access-date=November 9, 2014}}</ref> and independently by Tim Hochberg,<ref>{{cite mailing list |title=How do you pronounce "__" (double underscore)? |first=Tim |last=Hochberg |date=Sep 26, 2002 |mailing-list=python-list |url=https://mail.python.org/pipermail/python-list/2002-September/157561.html |access-date=November 9, 2014}}</ref> within minutes of each other, both in reply to the same question in 2002.<ref>{{Cite web|url=https://wiki.python.org/moin/DunderAlias|title=DunderAlias - Python Wiki|website=wiki.python.org}}</ref><ref>{{cite mailing list |title=How do you pronounce "__" (double underscore)? |first=Pat |last=Notz |date=Sep 26, 2002 |mailing-list=python-list |url=https://mail.python.org/pipermail/python-list/2002-September/137816.html |access-date=November 9, 2014}}</ref>