a question about return values and data query

Hi Everyone
    I have to questions:
    1) Is it possible to return sth formatted string like this:
        return  <Document>{$Document/HasDomain/@id /data()+"%%"+$Document/Time/text()}</Document>
        So far it shows errors.....I dont know if there are alternatives.
    2) I have data like this
          <Documents>
         <Document id="doc1">
             <Date>yyyy-mm-dd</Date>
             <HasIP ip="ip1">
             <HasDomain domain="domain1">
             <HasDomain domain="domain2">
          </Document>
         <Document id="doc1">
              <Date>yyyy-mm-dd</Date>
             <HasIP ip="ip2">
             <HasDomain domain="domain1">
             <HasDomain domain="domain3">
          </Document>
     </Documents>
     <IPs>
           <IP id="ip1">
             <data>111.111.111.111</data>
          </IP>
          <IP id="ip2">
             <data>111.111.111.112</data>
          </IP>
     </IPs>
     <Domains>
          <Domain id="domain1">
             <data>abc.com</data>
          </Domain>
          <Domain id="domain2">
             <data>edf.com</data>
          </Domain>
          <Domain id="domain3">
             <data>abc.com</data>
          </Domain>
      <Domains>
       I m trying to get all domains from documents that are within the following time period.
       for $Document in doc('test')//Document
       let $datestr := $Document/Date/text()
       let $date := xs:date($datestr)
       where $date<=xs:date("2010-05-02") and $date>xs:date("2010-05-01") and $Document/HasDomain
       return  <Document>{$Document/HasDomain, $Document/Time/text()}</Document>

for $Document in doc('docs.xml')//Document[xs:date(./Date/text()) <=
xs:date("2010-05-02")]
   return <Document>{
     for $d in $Document/HasDomain/@domain/data()
       return <Domain>{attribute{"id"}{$d},
                       attribute{"data"}{doc('domains.xml')//Domain[@id/data()=$d]/data/text()}}
              </Domain>}
          </Document>

<Document>
   <Domain id="domain1" data="abc.com"/>
   <Domain id="domain2" data="edf.com"/>
</Document>
<Document>
   <Domain id="domain1" data="abc.com"/>
   <Domain id="domain3" data="abc.com"/>
</Document>