I have a Galois group that I'm tying to determine:

f=x^5 - 792*x^4 + 71280*x^3 + 39517632*x^2 - 7519640832*x + 314605513728;

d=3;

A=-9504*d^2;

B=365904*d^3;

R.<y>=K[];

g= y^2 - a^3-A*a-B;

L.<z> = NumberField(y^2 - a^3-A*a-B);

G=L.galois_group();

I have a couple issues: When I type G[1], it says GaloisGroup_v1 is not subscriptable

The second is the output for G says [10,-1,1,'C(10)=5[x]2']. I know this is the PARI label and the last entry is the GAP 4 label. But for the life of me I cannot find anywhere where it explicitly tells me what C(10)=5[x]2 means