Add is a procedure used to add the String value in AItem to the Value for the thread-safe data type. 

Add calls Lock to enable resource protection for Value prior to adding the contents of AItem to the thread-safe data type. 

Adds calls Unlock to disable resource protection for Value when AItem has been added, or an exception is raised. 

Use AddObject to add a string with an associated object instance to the thread-safe data type. 

Use Remove or Clear to delete one or all items in the thread-safe data type.

TIdThreadSafeStringList.AddObject 

TIdThreadSafeStringList.Clear 

TIdThreadSafeStringList.Lock 

TIdThreadSafeStringList.Unlock 

TIdThreadSafeStringList.Remove