In Australia, under CAO 40.1.0 (Pilot Licences and ratings - General Provisions) "Instrument flight time" is defined as
<font face="Verdana, Arial, Helvetica" size="2">time during which a pilot is piloting an aeroplane solely by reference to instruments and without external reference points."</font>
Leaves things pretty vague from a legal view, and I have had FOI's interpret that as including Night VFR without a horizon reference (i.e. remote from ground lighting.)
CASA issued an Aeronautical Information Circular (AIC) titled "logging of Flight time" a while ago that restricted the definition to flight in IMC, either on autopilot or hand flying, but that was probably an opinion of someone within CASA, unsupported by law or court precedence. That AIC has since been cancelled.