about scheduling parameters?

Hi Gurus,

i am confused about scheduling paremeters. where we can set the scheduling type as Lead time scheduling or Basic Date Scheduling.How sap knows this.

i understand that Basic date scheduling means system will consider only the Material Master dates. Lead time scheduling means system considers The Time in Routing. is this currect.

what about Floats in which Scheduling type system takes these floats. i have gone through some stuff and not able to get a clearity please help me to understand the production order scheduling.

Thanks&Regards,
Venkat.