Operations That Are Available/NotAvailable via Force.com and Metadata API

Hello EveryOne,

In this Post I am telling you about Operations that are available/notAvailable via Force.com and Metadata API .

In my project I want to change api name of all custom fields in my all custom object, Actually I want add a prefix in api name of custom fields. So I took my project into eclipse and change the api name of the field in xml file of every Object.(I thought it would be take less time ) and save it. Then I notice some thing which i am sharing here:

Operations that are available via Force.com and Metadata API
(we can do that things by modifying the xml of object )

   1. Add new fields to an object
    2.Make minor changes such as label, field lengths, etc.
    3.Change the ReferenceTo (eg from Account to Contact) for a field
    4.Changed a field type (eg from currency to number). Logically, some conversions might not be  possible?

Operations that are not available via Force.com and Metadata API(we can't do that things by modifying the xml of object )

    1.Cannot change the API name of an existing field. It will simply create the new field.
    2.Cannot delete existing picklist values
    3.Cannot delete fields
    4.Cannot change some field type (eg tried to change afield from autonumber to text but it didn’t      make the change).

Let me know if it is useful for you.
   
Thanks

Ashlekh Gera.