This script also uses the web scraping capabilities of DbfScript, loading information from a website to retrieve the current Mexican exchange rate:

 var #updatetime = load(&root/Currency[Name="MXN (Banco de Mexico)"])
 if (SetTime(Today(), #updatetime/UpdateTime) < Now()) then
     var #rate = load(&root/Currency[Name="MXN (Banco de Mexico)"])
     if (not (IsHoliday(#rate/HolidaySchedule, Today(), True))) then

         var #rateEntry = load(&root/Currency[Name="MXN (Banco de Mexico)"]/HistoricRate[EffectiveDate=Today()])

         if (NotExists(#rateEntry)) then

             // get date
             call tok:LoadUrl("http://www.banxico.org.mx/tipcamb/llenarTiposCambioAction.do?idioma=en")
             call tok:SkipTo("FIX")
             call tok:SkipTo("class")
             call tok:SkipTo(">")
             var #date = tok:NextDate()

             if (#date == Today()) then

                 // get rate
                 call tok:SkipTo("style")
                 call tok:SkipTo("id")
                 call tok:SkipTo(">")
                 var #rate = tok:NextNum()

                 insert record ( EffectiveDate = Today(), Rate = 1 div #rate, Source = "Banco de Mexico" ) for &root/Currency/HistoricRate at &root/Currency[Name="MXN (Banco de Mexico)"]/HistoricRate

             end if
         end if
     end if
 end if