Meaning of some of the System.Reflection.MethodAttributes enum fields

I don't understand meaning of two fields in System.Reflection.MethodAttributes enum: MethodAttributes.SpecialName and MethodAttributes.RTSpecialName. In particular, they are being in dynamic creation of class constructor:

TypeBuilder tb = GetTypeBuilder();   
ConstructorBuilder constructor = tb.DefineDefaultConstructor(MethodAttributes.Public | MethodAttributes.SpecialName | MethodAttributes.RTSpecialName);

ECMA-335 description is as cryptic as MS description.

rtspecialname indicates that the name of this item has special significance to the CLI. There are no currently defined special type names; this is for future use. Any item marked rtspecialname shall also be marked specialname.