I want to know the relationship between the followind tables: tfgld106, tfgld410 and tfgld418 becouse of I want to obtain all details for each tfgld106 line.

Any help will be appreciate.

Thanks

The link between tfgld106 and tfgld410 is a 1:n relation, with the following mapping of fields:
where (tfgld410.ttyp = tfgld106.otyp)
and (tfgld410.docn = tfgld106.odoc)
and (tfgld410.btno = tfgld106.obat)
and (tfgld410.lino = tfgld106.olin)
and (tfgld410.dbcr = tfgld106.dbcr)

The link between tfgld410 and tfgld418 is easy:
tfgld418._index1 = tfgld410._index1

When iterating the whole, don't forget to also include tfgld417, where (most of) the credit lines are stored.