§2.6.(a) Externalized roles of a base team

If the base class of a role T1.R1 is again a team T2, roles of that team T2 can be externalized (see §1.2.2) using base as their type anchor. Given that R2 is a role of T2, one could write:

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public team class T1 {
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  protected class R1 playedBy T2 {
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    protected R2<@base> aRoleOfMyBase;
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  }
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}

This syntax is only legal within the body of the role T1.R1 which is bound to the team T2 containing role R2. A static type prefix can be used to disambiguate a base anchor, so the explicit variant of the above type would be R2<@R1.base>.
It is not legal to use a type anchor containing base as an element in a path of references like <@base.field> or <@field.base>.