Enterprise Search web service in SharePoint

I have a question to Enterprise Search in SharePoint. I use this functionality over web service (.../_vti_bin/search.asmx). There are 开发者_开发问答some standart set of attributes (Name, Title...) returned as search result. For more attributes I created new "Metadata Property Mappings" and started full crawl, to be sure attributes in index will be updated. So here my questions:

1. Some of the attributes are in search results empty (for example property mapped on ows_BaseName). Is it a security issue?

2. I need uniquely identify object returned from search (to this time only files). So I want to use ows_GUID, because I need to get more informations from list service about this object. But I can't find property ows_GUID in list of properties in "Metadata Property Mappings". Can I map any property?

3. Actually if I could map all properties in "Metadata Property Mappings", I didn't need to use extra call on List web service. But if I can't, how can I uniquely identify object returned from search service to query a List service?

Regards

Anton Kalcik

I know one thing for sure, ows_Guid can't be used, call it a bug. The last one not sure what you mean.