I have got a PHP script (CMS) which generates ISO-8859-1 content (in the background there is also a database with Latin1 data). To visualize the data on mobile devices I use jQuery Mobile 1.3.1. In general there is no problem with character encoding if you use the correct meta tag in your HTML:
<meta charset="iso-8859-1" />
However jQuery Mobile has got this default setting:
$.mobile.ajaxEnabled = true;
So jQuery Mobile will automatically handle link clicks and form submissions through Ajax, when possible.
This is a very smart feature, but it destroys some special characters like german umlaute and you get this nasty characters: �