chaley did a similar for me back in 2010
Code:
program:
test( field('series'),
strcat(
substr(field('series'), 0, 1),
template("-series/{series}/{series_index:0>2s}-{title}_{id}_{authors}")
),
template("00noseries/{author_sort[0]}_authors/{authors}/{title}_{id}_{title}-{authors}")
)
You will see a
base level to avoid a huge clutter (and possibly overload a root folder)