If you are here you should have already read about HttpParameters.
Specifically you should read about the Accept header. This header is highly underestimated. The reason for this is that it often gets changed by proxy servers and in the mobile space by WAP gateways.
The header, in short, contains a list of content formats that are accepted by the browser or that the browser is able to handle. What is very important is the order. Preferred formats are listed before other formats.
Let's review sample header that we saw in the Accept page:
application/xhtml+xml, application/vnd.wap.wmlc;Type=4365, application/vnd.wap.wmlc;Type=4360, application/vnd.wap.wmlc;Type=1108, application/vnd.wap.wmlc;Level=1.3, application/vnd.wap.wmlc, application/vnd.wap.wmlscriptc, application/vnd.wap.multipart.related, application/vnd.wap.multipart.mixed, application/x-up-device, application/vnd.phonecom.mmc-wbxml;Type=4364, application/vnd.phonecom.mmc-wbxml, application/vnd.phonecom.im, application/octet-stream, application/vnd.openwave.pp, application/vnd.wap.sic, application/vnd.wap.slc, application/vnd.wap.coc, application/vnd.uplanet.bearer-choice-wbxml, application/vnd.uplanet.signal, application/vnd.uplanet.cacheop-wbxml, application/vnd.uplanet.alert-wbxml, image/vnd.wap.wbmp;Type=0, application/*, audio/iMelody, audio/midi,text/x-hdml, image/mng,image/x-mng,video/mng,video/x-mng,image/bmp,text/vnd.wap.wml
The very first mime type is application/xhtml+xml, one of the last ones is text/x-hdml.
application/xhtml+xml is the mime type for xHTML-MP.
For this browser, the preferred content format is xHTML-MP, then we can see application/vnd.wap.wmlc, which is compiled WML. Plain WML is the last of the accepted contents, infact the last mime type is text/vnd.wap.wml, this means that the browser prefers xHTML-MP, alternatibely a compiled version of WML, alternatively HDML or lastly plain WML.
If you have the ability to provide pages using xHTML-MP as a markup, you should do so, alternatively compiled WML, or HDML or plain WML. You should NEVER send a content format that is not listed here, because the device will not be able to handle it properly.
As a side note, compiled WML is most likely generated by wap gateways so you won't need to both generating it yourself, if your visitors access the web through it.