Required Browser Capabilities

For a browser to work correctly, it must include two capabilities that allow the browser to be identified at run time. The required capabilities are:

  • User-Agent. This capability names the browser.

  • Accept. This capability indicates the types of documents the browser can open.

These capabilities are part of HTTP standard information and appear in HTTP request headers sent from a browser. For example, a request from an HTML5 browser sent to a Web application might include the following lines:

Accept: image/gif, image/x-xbitmap, image/jpeg, image/pjpeg, */* 
User-Agent: Mozilla/5.0

Both the User-Agent and Accept capabilities must be included because at run time the User-Agent is checked to identify the browser. If the User-Agent is not recognized, then the values for the Accept parameter in the header are compared to the Accept parameters of the browsers listed in the Web Browser Administration screen to find the browser with the most closely matching Accept parameters.

In addition to the User-Agent and Accept capabilities, if a browser is based on an existing parent browser, then it must include the Parent capability.

Note: Parent browsers frequently do not have the User-Agent and Accept capabilities because parent browsers are intended to serve as containers of other capabilities that can be inherited. If a browser does not have its own User Agent and Accept capabilities, then it is acting as a parent of another browser that has these capabilities.