Would it be feasible to use a LRT file without the nameserver parameter?

Hello all,

Our company entered in a maintenance project of some SBCs and we've discovered that one cluster is using an LRT that lacks from the the usual namespace definition.

<?xml version="1.0" encoding="UTF-8" standalone="yes"?>

<route><user type="E164">some_number</user><next type="regex">!(^.*$)!sip:some_number@some_domain!</next></route>

(...)

</localRoutes>

We would expect the second line to be something like the following:

<localRoutes xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">

We have to admit that the SBC is working fine, even for LRT routed numbers but we would like to know if anyone has a reference or an experience on using LRTs without this line.