ID param in the form

Hi,

Could you tell me more details about ID, which is requried to submit a file?
I went through the manual at http://writer.zoho.com/public/help/writer.remoteapi/fullpage,
but still i wonder what it is all about.

Do i have to generate it by myself in the first place,
and then am gonna have to keep it in my server for reference?
Or it's YOU that generate it?

Plus, any rule or convention to conjure it up?
Or just OK to leave it up to me?

Takash