[aprssig] Gain reference in PHG?

[Tapio Sokura]

I noticed the recent discussion about PHG in digis and remembered a 
small problem I once ran into: Is the antenna gain figure in PHG 
relative to dBi or dBd? Or something else? The 1.01 APRS specification 
does not say what the reference is and without a reference a plain dB 
value tells nothing.

   Tapio