Учитывая преимущество единообразия (в других местах T также приводится как  расширение T0), наверное всё же правильнее исправить предложение выше

Variables of a pointer type P assume as values pointers to variables of some type T. It must be a record type.The pointer type P0 is said to be bound to T0, and T0 is the pointer base type of P0.Pointer types inherit the extension relation of  their base types, if there is any. If a type T is an extension of T0 and P is a pointer type bound to T, then P is also an extension of P0.

а также в 4 главе.

1. If a type T is defined as POINTER TO T1 (see 6.4), the identifier T1 can be declared textually following the declaration of T, but it must lie within the same scope.

на

1. If a type P is defined as POINTER TO T (see 6.4), the identifier T can be declared textually following the declaration of P, but it must lie within the same scope.