Added the following text on the interaction with rate limiting at the end of the
first main paragraph:

                                                        If the number
   of active routing state items corresponds to a rate of Queries that
   will stress the rate limits applied to D-mode traffic
   (Section 5.3.3), nodes MUST increase the timer for new items and on
   the refresh of existing ones.  A suitable value is twice the number
   of items divided by the rate limit in messages per second, which
   leaves a factor of two headroom for new routing state creation and
   Query retransmissions.

and the next paragraph resolves the Query timing contradiction:

   The Querying node MUST ensure that a Query is received before this
   timer expires, if it believes that the signalling session is still
   active; otherwise, the Responding node MAY delete the state.

The text in 4.4.3 is strictly contradictory, since some of it talks about the
need to generate a Query within a certain time, whereas the actual requirement
is to have it received. In addition, clearer guidance is needed on how to select
timers that will keep the generated Queries within the rate limiting rules.