Hi, Let me explain my question using the following example:

```
{a, b, c, d, e, f}::Indices.
\eta_{a b}::Metric.
\eta_{a}^{b}::KroneckerDelta.
F_{a}^{b} G_{b c} + F^{b d}G_{d a c b};
@factor_out!(%){F_{a b}};
```

In this case the `@factor_out`

doesn't work because there is no `F_{a b}`

in the expression. On solution might be transform the `F_{a}^{b}`

and `F^{b d}`

into `F_{a b}`

using `KroneckerDelta`

and the `@substitute`

command and then factor it out. But this solution for a long expression with many indices is really cumbersome. I would like to know whether exists any more genuine solution.

Cheers!