Miva - Sitelinks Search Box Schema
<div itemscope itemtype="http://schema.org/WebSite">
<meta itemprop="url" content="http://&mvte:global:domain:name;/"/>
<form itemprop="potentialAction" itemscope itemtype="http://schema.org/SearchAction">
<meta itemprop="target" content="http://&mvte:global:domain:name;/SRCH.html?Search={search_term_string}"/>
<input itemprop="query-input" type="text" name="search_term_string" required/>
<input type="submit"/>
</form>
</div>