search for valid types in the api-doc, do a search for: "template::data::validate::"
like here:
https://openacs.org/api-doc/proc-search?query_string=template%3A%3Adata%3A%3Avalidate%3A%3A&search_type=Search&name_weight=5¶m_weight=3&doc_weight=2
use the oacs 4.6.2 and it has a float validation.
you'll use as (if ain't worng)
{q1:float {label " Planning - Hours"}
{optional}
{section " Program Management"}
{html {size 5}} }
I just created a naturalnum also, I'll submit the patch later =)