No-no-no, that would be too trivial.
Before posting I trying to search using attribute uidNumber,
attributetype ( 22.214.171.124.126.96.36.199 NAME 'uidNumber'
DESC 'An integer uniquely identifying a user in an administrati
SYNTAX 188.8.131.52.4.1.14184.108.40.206.27 SINGLE-VALUE )
with the filter 'uidNumber <= 1000' and still got no answers. Your supposition may be correct, but it does not answer the second question - how can I do a search with given filter, treating numbers as numbers?