Are you storing ASCII text, binary data, INTs FLOATs - what? Or is that the problem - you don't know?

Just pick one that works. People don't seem to argue with ASCII representations of deciaml numbers! Though it's hardly elegant.
If you follow the thread through, I don't change the basic definition of anything away from what's being done already. So, the ReplayGain is still a +/- number relative to 83+6dB (i.e. 89dB).
ReplayGains are typically between +12 and -15. One decimal place is more than enough, but some formats store 2.
Peak values can be below or above digital full scale, and have been stored as both simple normalised decimals using ASCI characters (e.g. 1.0000 for digital full scale), or binary representations with various formats. My preference at the moment is the 32-bit INT method described in that thread. If using an ASCII representation of decimal, you need at least enough accuracy to match 24 bits.
As for other values, I would appreciate it very much if you would include the proposed extensions in Matroska. (see
http://www.hydrogenaudio.org/forums/index....showtopic=15445 )
(in the following, by "you need" I mean "you need to allow for a maximum of...")
1. You need one "(ReplayGain) undo adjustment" per track (always optional).
It would have a similar range to the actual ReplayGain values, but accuracy needs to be greater - several decimal places, though only one will normally be used.
2. You need one "ReplayGain calculation method" per ReplayGain value (optional for legacy values which don't have it already, but should be filled in for newly calculated ReplayGains).
Decimal value - probably 1, 2 or 3, but maybe 1.1, 2.01 - depends how many different tweaks and/or complete changes to the calculation are proposed!
3. You need one "ReplayGain lossy approximation" per ReplayGain or peak value (optional for legacy values which don't have it already, but should be filled in for newly calculated ReplayGains, or for any ReplayGains copied across when transcoding)
0 or 1.
4. You need one "ReplayGain user adjustment" per track (always optional).
Range same as other ReplayGain values.
5. You need one "ReplayGain RealLife adjustment" per track (always optional).
Range same as other ReplayGain values.
Does this help? Or hinder?

Cheers,
David.
P.S. If I appear to ignore you, it's only because I might not get chance to check HA next week.