Compatibility mode
A compatibility mode is a software mechanism in which a software either emulates an older version of software, or mimics another operating system in order to allow older or incompatible software or files to remain compatible with the computer's newer hardware or software. Examples of the software using the mode are operating systems and Internet Explorer.
Operating systems
A compatibility mode in an operating system is a software mechanism in which a computer's
This differs from a full-fledged emulator in that an emulator typically creates a virtual hardware architecture on the host system, rather than simply translating the older system's function calls into calls that the host system can understand.
Examples include Classic Mode in
Internet Explorer
"Compatibility View" is a compatibility mode feature of the web browser Internet Explorer in version 8 and later. When active, Compatibility View forces IE to display the webpage in Quirks mode as if the page were being viewed in IE7.[1][2] When compatibility view is not activated, IE is said to be running in native mode. In IE11, a user can turn on compatibility mode for a web site by clicking the Gears icon and clicking Compatibility View Settings.
IE8+
To avoid this situation, IE8 implemented a form of version targeting whereby a page could be authored to a specific version of a browser using the X-UA-Compatible
declaration either as a meta element or in the HTTP headers.[3]
In order to maintain backwards compatibility, sites can opt into IE7-like handling of content by inserting a specially created meta element into the web page that triggers compatibility mode in the browser, using:[4]
<meta http-equiv="X-UA-Compatible" content="IE=EmulateIE7" />
A newer version of the browser than the page was coded for would emulate the behavior of the older version, so that the assumptions the page made about the browser's behavior hold true.
Microsoft proposed that a page with a
Peter Bright of Ars Technica claimed that the idea of using a meta tag to pick a specific rendering mode fundamentally misses the point of standards-based development but positioned the issue as one of idealism versus pragmatism in web development, noting that not all of the Web is maintained, and that "demanding that web developers update sites to ensure they continue to work properly in any future browser version is probably too much to ask."[5]
The result for IE 8 Beta 1 was that it could render three modes: "Quirks," "Strict," and "Standard." When there is an old
Microsoft maintains a list of websites that have been reported to have problems in IE8's standards mode, known as the compatibility view list. When a user enables this list IE8 will render the websites in the list using its compatibility view mode.[7] The list is occasionally updated to add newly reported problematic websites, as well as to remove websites whose owners have requested removal. The Internet Explorer team also tests the websites on the list for compatibility issues and removes those where none are found.[8]
See also
- Windows XP Mode
- Legacy mode
- Backward compatibility
- Quirks mode
- Program information file (PIF)
References
- ^ "2.1.2.5 Compatibility View". [MS-IEDOCO]: Internet Explorer Standards Support Documentation Overview. Microsoft. 2015.
- ^ "Fix site display problems with Compatibility View". Microsoft Windows: How To. Microsoft. Retrieved 29 July 2015.
- ^ Aaron Gustafson (January 21, 2008). "Beyond DOCTYPE: Web Standards, Forward Compatibility, and IE8". Retrieved 2007-03-22.
- ^ MSDN "What's New in Internet Explorer 8" Archived 2008-04-18 at the Wayback Machine.
- ^ Peter Bright (January 24, 2008). "Wisdom and folly: IE8's super standards mode cuts both ways". Ars Technica. Retrieved 2008-03-21.
- CNetBlogs. Retrieved 2007-03-05.
- ^ "Understanding the Compatibility View List". MSDN. Microsoft. Retrieved 2009-09-06.
- ^ Scott Dickens (July 21, 2009). "Update on the Compatibility View List in Internet Explorer 8". IEBlog. Microsoft. Retrieved 2009-09-06.