WebDNA normally compares all fields in a database as though they were text, even if they look like numbers to you. Unless you tell it to compare a field numerically (or as a date), all comparisons are alphabetical.
If your database has a numeric field (Price, for instance) that you wish to compare numerically, you would put something like the following in the search criteria:
http://Results.tpl?command=search&gePricedata=99.95&Pricetype=num
Why is this important? Imagine that WebDNA is comparing two text fields that happen to contain numbers in them:
Compare "10.95" to "9.95" -- when compared alphabetically, WebDNA looks at the first letter in both fields and sees "1" and "9", respectively. In this case, it would (wrongly) assume that "9" is greater than "1" (which in an alphabetical sense is true), and would sort "9.95" after "10.95". This is probably not what you meant.
When compared numerically, the two numbers would sort correctly.