Hi, i'm quite new on this so forgive if obvious or cautioned against in the documentation...

but i get some funny stuff with canonicalise

```
{a, b, c, d, e, f, g}::Indices(position=independent)
F_{a b}::AntiSymmetric;
{\cal F}_{a b}::AntiSymmetric;
example1:= F_{a b} F_{c d} - F_{a c} F_{b d} ;
canonicalise(_);
```

Here canonicalise correctly does nothing and returns `F_{a b} F_{c d} - F_{a c} F_{b d}`

.

However

```
example2:= {\cal F}_{a b} {\cal F}_{c d} - {\cal F}_{a c} {\cal F}_{b d} ;
canonicalise(_);
```

returns for me `2 {\cal F}_{a b} {\cal F}_{c d}`

.

Clearly avoiding the usage of the {\cal F} is the work around but even so.

Cheers

D