Codeplug ver., z19 and s19 flashstrap? MTH800

[zeus]

I'm a newbie here so sorry if this is lame but I have a few questions about the ******** stuf.

1. The radio has firmware and it's a *.z19 file about 10Mb. so what is a .s19 1,5Mb file for?

2. I've seen .s19 files 90-500Kb witch have "flashstrap" in there name and I tried to find something about flashstrap and the only info I found is closer to GSM phones of ******** and it's more of entering flashstrap mode to flash a phone, so what is it? or what practical use would it make with a MTH800?

3. How does the firmware version go in pair with the codeplug version, I mean if the radio has R07.000.xxxx are there any limits with the codeplug structure and default version? Or is there no difference and its possible to load a 0x0070, 0x0064 codeplug into an older firmware radio?

4. What is a *.stf file in the context of Tetra and/or CPS?

Thanks for your help