@eschwartz: the following fragment detects float vs integer. It might eliminate the need to regexp?
Code:
program:
dex=field('series_index');
i=format_number(dex, "{:02d}");
f=format_number(dex, "{:04.1f}");
isInt=cmp(f, i, '', 'yes', '');
result=test(isInt, i, f)