General Question Question about the ID number of big and small bodies


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Mar 5, 2008
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The project I am working on basicly is a meshup of Asterank and Nasa's Trajectory Browser. Asterank is a wrapper around the JPL Small Body Database and currently my starting point. In the output I am getting, amongst many other values, there seem to be 4 ways to uniquely identify an asteroid:

id: a0162173
name: Ryugu
full name: 162173 Ryugu (1999 JU3)
spkid: 2162173.0

At the moment, I use the spkid as a primary identifier since it's the only one which I can use without changing something. The field 'id' for example, would require me to strip the 'a' (which stands for asteroid I assume).

When working with this data, I've come across a few questions which I could use some help with:
1) What is the main difference between id (without prefix) and spkid?
2) What does spk stand for? I assume the s stands for small.
3) I know from inspecting the Trajectory output, that even big bodies like the sun and earth do have a spkid. The sun's spkid is 10. Earth is 399.

From this pattern, I assume Mercury is 199 and Mars is 499. But I am not sure, because I can't find a source. I expect that Pluto's spkid is still 999. But that's all it is, an assumption. What happens if planet IX is found? Is there a source somewhere that lists these spkid's of bigger bodies?

Thanks for any help.