Hi, I am trying to develop an alternative program to MeshesSL that will be less buggy as well as having features such as batch SLM to DAE conversion and link separation. I know that the SLM files are stored in the data.db2.x.1 and data.db2.x.1.0 files within the appdata folder for the viewer, but I am not entirely sure how each SLM file is identified.
I would greatly appreciate it if someone could provide me with information regarding SLM identification.
Also, if anyone could tell me how to possibly extract the dae file from SLM files. I have been looking on the SL wiki about SLM file architecture, but it is not very specific.

Hello, I also would like to learn the details. How SLM files are encoded? Eventually where could I find Mesh Helper or even old MeshesSL sourcecode? Thank you in advance for help! <3

when you add a xml file to MeshesSL it makes always 2 folders
local - appdata- MeshesSL
1 dae folder the other is slm folder
you can open both with notepad ++ to look inside
handy for your info

No no, my question is how to get data from SLM file without using MeshesSL - in what way MeshesSL decodes the original SLM asset files that are stored in cache? When I open the cache file with notepadd++ it shows ugly signs - which means it is binary file encoded in special way. I am sure there is some kind of way to read this - like which bytes range corresponds to which float number for example. 

And the reason I avoid using meshesSL or Mesh Helper is that they do not accpet standard input - so i can not automate parsing 10 XMLs through the program and instead i have to always manually choose XML one by one.

then google many about slm files on it

I did google! Otherwise I wouldn't ask the question here and instead post some tutorial here about it *giggles*
And I didn't find any answer for the issue. The only thing that I fould is this page:

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This explains the general architecture of the SLM file. But it doesn't show exactly how every data is stored (which bytes means which data).
Maybe these data are stored using some known tree or table algoritm (for example xml and json are famous tree encodings for data structures - though they are text-readable - this one is clearly binary for maximial data compression) - I don't know. The MeshesSL and Mesh Helper creation team somehow found it out.

I would make all the programming myself - just need the basic info how to read the slm file. Any site, documentation, tutorial, just anything! :D Evem Mesh Helper or MeshesSL sourcecode could help in some way - does not have to be current one - even old version. I know how to binarily read files I just need to know the encoding.

I couldn't find any answer anywhere so I opened firestorm code and started digging there.
I figured out the binary llsd format and how to read. 

I discovered that SLM file is made from decompressed binary llsd header and compressed binary llsd data.
I found problem though with decompression of the data. Having problems understanding how the decompression algorythm works (some weird pointers there doing not fully sure what).

If someone knows how llsd compression works please PM me or write on this thread - me and others will greately appreciate it <3

Yay! I found it! It was zlib best compression!