$AL is the head for dummy indices which may be
introduced by different functions. By default it is unset, but may be
set to anything.
Uncontract[ScalarProduct[p, q], q, Pair -> All]\overline{p}^{\text{\$AL}(\text{\$11})} \overline{q}^{\text{\$AL}(\text{\$11})}
$AL = \[Mu];
Uncontract[ScalarProduct[p, q], q, Pair -> All]\overline{p}^{\mu (\text{\$12})} \overline{q}^{\mu (\text{\$12})}
$AL =.;