What's FSW eaxctly?

[Milad Vafaeifard]

Hello!
we are working in sign language research and development, one thing I really 
need to know that what's FSW exactly working, of course I little know what is 
Code,
 
Let me tell you example:
in a sign "Water" :
AS18610S20600S30004M534x548S20600512x512S30004482x482S18610492x518
A what is it for?
S18610 key symbol i know this.
S20600 key symbol i know this.
S30004 key symbol i know this.
but other : M 534x548 S20600 512x512 S30004 482x482 S18610 492x518

one thins that i really need to know what's nnnxnnn for example: 534x548
i know that is width and height but where start and where end?
could you help me this code how works? can you explain this to me more detail 
each character?

Thank you very much!