This tag helps to link two informationSet. Basically we can create a inputbox to select data from other InformationSet. The input box can be a Drop Down, Radio Button, Check Box etc. See below example:
 
<field name="shippingcountry">
  <title>Country </title>
  <hints/>
  <type>informationTag</type>
  <validation>
      <rule>
          <type>notEmpty</type>
          <err-message>Please select a country</err-message>
      </rule>
  </validation>
  <parameters>
      <parameter name="information_type">country</parameter>
      <parameter name="key">id</parameter>
      <parameter name="val">title</parameter>
      <parameter name="inputType">selectTag</parameter>
  </parameters>
  <tag-attributes>
      <attribute name="id">shippingcountry</attribute>
  </tag-attributes>
</field>
 
Parameter:
For InformationSet we pass some parameter:
information_type: This parameter is the name ofInformationSet  that we want to call.
key: Field name used as value of Input filed
val: Lable of the field in HTML Input box
inputType: Type of input to render in Interface.