Active Directory user object delegation - Write permissions for certain fields

I am trying to delegate write permissions to certain fields in user objects in the user ou.   I am able to delegate rights to certain fields without any problems...but I have yet been able to find the proper field names to delegate for other fields.   More directly..  I would like to give  a global group write access to the email field {General tab/Email Field} and I would also like to grant write access to office field {General tab/Office Field}   I have been able to grant write access to few other fields that I wanted {by delegation wizard or by manually adding rights under advanced options}.  In the end I just need to figure out what the field names are called in the delegate wizard menu {same names are used in advanced options}  Any help would be appreciated.  Thanks.