Often when you are conducting a synchronisation or migration of data you only want to concentrate on a subset of the data. I the case of Dynamics CRM Online or 2011 Data Synchronisation Studio allows you to specify a filter using the standard FetchXml syntax.
A great way to get the correct fetch xml is to create an advanced find and then click the 'Download Fetch XML' button. This downloads a txt file with the complete xml in it. Copy the filter node and paste into the fetch XML fields in Data Sync.
<filter type="and"> <condition attribute="statecode" operator="eq" value="6" /> </filter>
<filter type="and"> <condition attribute='importsequencenumber' operator='eq' value='1' /> </filter>
It is important to note that we are including the 'filter' clause in Fetchxml statement. Other operators are available:
<filter type='or'> <condition attribute = 'createdon' operator='today'/> </filter>
More examples of the FetchXml syntax can be found on the Microsoft Site.