what is the difference between AliasAssign and AliasReassignment

[FabArd]

On Monday, 27 March 2023 at 16:59:29 UTC, FabArd wrote:
> Hi,
>
> I don't understand a point in the grammar :
>
>     5.4.6 AliasAssign:
>         Identifier = Type
>
>     5.4.7 AliasReassignment:
>         Identifier = StorageClasses(optional) Type
>
> AliasAssign rule is included in the AliasReassignment rule.
>
> Why there are two rules in the grammar to describe the same 
> thing?

It seems that AliasReassignment rule is an orphan rule. Indeed it 
is not used anywhere else in the whole grammar.