Whether to show the next button on a survey page.
<survey> <surveypage>
A value of 1 indicates the button will be shown, 0 indicates it will not.
The following displays the value of shownextbutton in a text stimulus:
<text sometext>
/ items= ("shownextbutton = <% surveypage.page3.shownextbutton %>")
</text>
The following displays the value of shownextbutton in an instruction page:
<page somepage>
shownextbutton = <% survey.mysurvey.shownextbutton %>
</page>