XPontus is an open source XML editor. It may be possible to adapt XPontus code to provide validation capabilities.
XPontus does XML well-formness validation as well as schema based validation.
<disposition_code>60</disposition_code </line_item> Error at line:109,column:5 The end-tag for element type "disposition_code" must end with a '>' delimiter.
<disposition_code>60 </line_item> Error at line:109,column:7 The element type "disposition_code" must be terminated by the matching end-tag "</disposition_code>".
<disposition_code></disposition_code> The document is invalid! Error around line : 108,column:46 Content of element "disposition_code" is incomplete